diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 40b52fd..dd3194c 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -9,14 +9,15 @@ on:
 jobs:
   build:
     uses: Workiva/gha-dart-oss/.github/workflows/build.yaml@v0.1.7
+    with:
+      sdk: stable
 
   checks:
     uses: Workiva/gha-dart-oss/.github/workflows/checks.yaml@v0.1.7
+    with:
+      sdk: stable
 
   unit-tests:
-    strategy:
-      matrix:
-        sdk: [2.19.6, stable]
     uses: Workiva/gha-dart-oss/.github/workflows/test-unit.yaml@v0.1.7
     with:
-      sdk: ${{ matrix.sdk }}
\ No newline at end of file
+      sdk: stable
diff --git a/.github/workflows/publish.yaml b/.github/workflows/publish.yaml
index f978e2e..34a91e1 100644
--- a/.github/workflows/publish.yaml
+++ b/.github/workflows/publish.yaml
@@ -12,4 +12,6 @@ permissions:
 
 jobs:
   publish:
-    uses: Workiva/gha-dart-oss/.github/workflows/publish.yaml@v0.1.7
\ No newline at end of file
+    uses: Workiva/gha-dart-oss/.github/workflows/publish.yaml@v0.1.7
+    with:
+      sdk: stable
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c065297..1a307d9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# 5.0.0
+
+- **Breaking change**: Requires Dart 3.0 or above
+- Added support for Pub Workspaces (monorepos)
+
 # 4.1.1
 
 - Update the output of parse failures to include the path to the file which failed to parse
diff --git a/README.md b/README.md
index 6f08707..dc4a9e1 100644
--- a/README.md
+++ b/README.md
@@ -46,5 +46,24 @@ ignore:
   - analyzer
 ```
 
-> Note: Previously this configuration lived in the `pubspec.yaml`, but that
+> [!Note]
+> Previously this configuration lived in the `pubspec.yaml`, but that
 > option was deprecated because `pub publish` warns about unrecognized keys.
+
+## Pub Workspaces (monorepos)
+
+This package supports [Pub Workspaces](https://dart.dev/tools/pub/workspaces), a collection of packages in one repository. Workspaces allow Pub to share dependencies between your packages. Your top-level package's `pubspec.yaml` should have a `workspace` field that indicates which sub-packages should be included, like this:
+
+```yaml
+workspace:
+  - pkg1
+  - pkg2
+```
+
+and your sub-packages should have `resolution: workspace` in their `pubspec.yaml`s. For more information, see the linked documentation.
+
+**Running `dependency_validator` will always validate the package your terminal is in**. If you run the tool on the top-level workspace package, it will analyze the workspace package _and_ its sub-packages. To just analyze a sub-package, run the tool in its folder, or pass the `-C` argument:
+
+```bash
+$ dart run dependency_validator -C pkg1
+```
diff --git a/bin/dependency_validator.dart b/bin/dependency_validator.dart
index bc762f8..f90b97a 100644
--- a/bin/dependency_validator.dart
+++ b/bin/dependency_validator.dart
@@ -21,6 +21,7 @@ import 'package:logging/logging.dart';
 
 const String helpArg = 'help';
 const String verboseArg = 'verbose';
+const String rootDirArg = 'directory';
 const String helpMessage =
     '''Dependency Validator 2.0 is configured statically via the pubspec.yaml
 example:
@@ -45,6 +46,12 @@ final ArgParser argParser = ArgParser()
     verboseArg,
     defaultsTo: false,
     help: 'Display extra information for debugging.',
+  )
+  ..addOption(
+    rootDirArg,
+    abbr: "C",
+    help: 'Validate dependencies in a subdirectory',
+    defaultsTo: '.',
   );
 
 void showHelpAndExit({ExitCode exitCode = ExitCode.success}) {
@@ -78,5 +85,8 @@ void main(List<String> args) async {
     Logger.root.level = Level.ALL;
   }
 
-  await run();
+  Logger.root.info('');
+  final rootDir = argResults.option(rootDirArg) ?? '.';
+  final result = await checkPackage(root: rootDir);
+  exit(result ? 0 : 1);
 }
diff --git a/example/example.md b/example/example.md
index 32be703..22ce7db 100644
--- a/example/example.md
+++ b/example/example.md
@@ -1,4 +1,13 @@
-Either globally activate this package or add it as a dev_dependency. Then run:
+Either globally activate this package or add it as a dev_dependency:
+```bash
+# Install as a dev dependency on the project -- shared with all collaborators
+$ dart pub add --dev dependency_validator
+
+# Install globally on your system -- does not impact the project
+$ dart pub global activate dependency_validator
+```
+
+Then run:
 
 ```bash
 # If installed as a dependency:
@@ -8,16 +17,17 @@ $ dart run dependency_validator
 $ dart pub global run dependency_validator
 ```
 
-If needed, configure dependency_validator in your `pubspec.yaml`:
+If needed, add a configuration in `dart_dependency_validator.yaml`:
 
 ```yaml
-# pubsec.yaml
-dependency_validator:
-  # Exclude one or more paths from being scanned.
-  # Supports glob syntax.
-  exclude:
-    - "app/**"
-  # Ignore one or more packages.
-  ignore:
-    - analyzer
+# Exclude one or more paths from being scanned. Supports glob syntax.
+exclude:
+  - "app/**"
+
+# Ignore one or more packages.
+ignore:
+  - analyzer
+
+# Allow dependencies to be pinned to a specific version instead of a range
+allowPins: true
 ```
diff --git a/lib/src/dependency_validator.dart b/lib/src/dependency_validator.dart
index 926fe85..6a669d3 100644
--- a/lib/src/dependency_validator.dart
+++ b/lib/src/dependency_validator.dart
@@ -16,7 +16,6 @@ import 'dart:io';
 
 import 'package:build_config/build_config.dart';
 import 'package:dependency_validator/src/import_export_ast_visitor.dart';
-import 'package:glob/glob.dart';
 import 'package:io/ansi.dart';
 import 'package:logging/logging.dart';
 import 'package:package_config/package_config.dart';
@@ -28,24 +27,22 @@ import 'pubspec_config.dart';
 import 'utils.dart';
 
 /// Check for missing, under-promoted, over-promoted, and unused dependencies.
-Future<void> run() async {
-  if (!File('pubspec.yaml').existsSync()) {
+Future<bool> checkPackage({required String root}) async {
+  var result = true;
+  if (!File('$root/pubspec.yaml').existsSync()) {
     logger.shout(red.wrap('pubspec.yaml not found'));
-    exit(1);
-  }
-  if (!File('.dart_tool/package_config.json').existsSync()) {
-    logger.shout(red.wrap(
-        'No .dart_tool/package_config.json file found, please run "pub get" first.'));
-    exit(1);
+    logger.fine('Path: $root/pubspec.yaml');
+    return false;
   }
 
   DepValidatorConfig config;
-  final configFile = File('dart_dependency_validator.yaml');
+  final configFile = File('$root/dart_dependency_validator.yaml');
   if (configFile.existsSync()) {
     config = DepValidatorConfig.fromYaml(configFile.readAsStringSync());
   } else {
     final pubspecConfig = PubspecDepValidatorConfig.fromYaml(
-        File('pubspec.yaml').readAsStringSync());
+      File('$root/pubspec.yaml').readAsStringSync(),
+    );
     if (pubspecConfig.isNotEmpty) {
       logger.warning(yellow.wrap(
           'Configuring dependency_validator in pubspec.yaml is deprecated.\n'
@@ -53,29 +50,40 @@ Future<void> run() async {
     }
     config = pubspecConfig.dependencyValidator;
   }
+
   final excludes = config.exclude
       .map((s) {
         try {
-          return Glob(s);
+          return makeGlob("$root/$s");
         } catch (_, __) {
           logger.shout(yellow.wrap('invalid glob syntax: "$s"'));
           return null;
         }
       })
-      .where((g) => g != null)
-      .cast<Glob>()
+      .nonNulls
       .toList();
   logger.fine('excludes:\n${bulletItems(excludes.map((g) => g.pattern))}\n');
   final ignoredPackages = config.ignore;
   logger.fine('ignored packages:\n${bulletItems(ignoredPackages)}\n');
 
   // Read and parse the analysis_options.yaml in the current working directory.
-  final optionsIncludePackage = getAnalysisOptionsIncludePackage();
+  final optionsIncludePackage = getAnalysisOptionsIncludePackage(path: root);
 
   // Read and parse the pubspec.yaml in the current working directory.
-  final pubspecFile = File('pubspec.yaml');
-  final pubspec =
-      Pubspec.parse(pubspecFile.readAsStringSync(), sourceUrl: pubspecFile.uri);
+  final pubspecFile = File('$root/pubspec.yaml');
+  final pubspec = Pubspec.parse(
+    pubspecFile.readAsStringSync(),
+    sourceUrl: pubspecFile.uri,
+  );
+
+  var subResult = true;
+  if (pubspec.isWorkspaceRoot) {
+    logger.fine('In a workspace. Recursing through sub-packages...');
+    for (final package in pubspec.workspace ?? []) {
+      subResult &= await checkPackage(root: '$root/$package');
+      logger.info('');
+    }
+  }
 
   logger.info('Validating dependencies for ${pubspec.name}...');
 
@@ -92,7 +100,8 @@ Future<void> run() async {
   logger.fine('dev_dependencies:\n'
       '${bulletItems(devDeps)}\n');
 
-  final publicDirs = ['bin/', 'lib/'];
+  final publicDirs = ['$root/bin/', '$root/lib/'];
+  logger.fine("Excluding: $excludes");
   final publicDartFiles = [
     for (final dir in publicDirs) ...listDartFilesIn(dir, excludes),
   ];
@@ -132,14 +141,29 @@ Future<void> run() async {
   logger.fine('packages used in public facing files:\n'
       '${bulletItems(packagesUsedInPublicFiles)}\n');
 
-  final publicDirGlobs = [for (final dir in publicDirs) Glob('$dir**')];
+  final publicDirGlobs = [
+    for (final dir in publicDirs) makeGlob('$dir**'),
+  ];
+
+  final subpackageGlobs = [
+    for (final subpackage in pubspec.workspace ?? [])
+      makeGlob('$root/$subpackage**'),
+  ];
+
+  logger.fine('subpackage globs: $subpackageGlobs');
 
-  final nonPublicDartFiles =
-      listDartFilesIn('./', [...excludes, ...publicDirGlobs]);
-  final nonPublicScssFiles =
-      listScssFilesIn('./', [...excludes, ...publicDirGlobs]);
-  final nonPublicLessFiles =
-      listLessFilesIn('./', [...excludes, ...publicDirGlobs]);
+  final nonPublicDartFiles = listDartFilesIn(
+    '$root/',
+    [...excludes, ...publicDirGlobs, ...subpackageGlobs],
+  );
+  final nonPublicScssFiles = listScssFilesIn(
+    '$root/',
+    [...excludes, ...publicDirGlobs, ...subpackageGlobs],
+  );
+  final nonPublicLessFiles = listLessFilesIn(
+    '$root/',
+    [...excludes, ...publicDirGlobs, ...subpackageGlobs],
+  );
 
   logger
     ..fine('non-public dart files:\n'
@@ -193,7 +217,7 @@ Future<void> run() async {
       'These packages are used in lib/ but are not dependencies:',
       missingDependencies,
     );
-    exitCode = 1;
+    result = false;
   }
 
   // Packages that are used outside lib/ but are not dev_dependencies.
@@ -215,7 +239,7 @@ Future<void> run() async {
       'These packages are used outside lib/ but are not dev_dependencies:',
       missingDevDependencies,
     );
-    exitCode = 1;
+    result = false;
   }
 
   // Packages that are not used in lib/, but are used elsewhere, that are
@@ -235,7 +259,7 @@ Future<void> run() async {
       'These packages are only used outside lib/ and should be downgraded to dev_dependencies:',
       overPromotedDependencies,
     );
-    exitCode = 1;
+    result = false;
   }
 
   // Packages that are used in lib/, but are dev_dependencies.
@@ -251,7 +275,7 @@ Future<void> run() async {
       'These packages are used in lib/ and should be promoted to actual dependencies:',
       underPromotedDependencies,
     );
-    exitCode = 1;
+    result = false;
   }
 
   // Packages that are not used anywhere but are dependencies.
@@ -269,8 +293,7 @@ Future<void> run() async {
   if (packageConfig == null) {
     logger.severe(red.wrap(
         'Could not find package config. Make sure you run `dart pub get` first.'));
-    exitCode = 1;
-    return;
+    return false;
   }
 
   // Remove deps that provide builders that will be applied
@@ -285,30 +308,39 @@ Future<void> run() async {
           .any((key) => key.startsWith('$dependencyName:'));
 
   final packagesWithConsumedBuilders = Set<String>();
-  for (final package in unusedDependencies.map((name) => packageConfig[name])) {
+  for (final name in unusedDependencies) {
+    final package = packageConfig[name];
+    if (package == null) continue;
     // Check if a builder is used from this package
-    if (rootPackageReferencesDependencyInBuildYaml(package!.name) ||
+    if (rootPackageReferencesDependencyInBuildYaml(package.name) ||
         await dependencyDefinesAutoAppliedBuilder(p.fromUri(package.root))) {
       packagesWithConsumedBuilders.add(package.name);
     }
   }
 
   logIntersection(
-      Level.FINE,
-      'The following packages contain builders that are auto-applied or referenced in "build.yaml"',
-      unusedDependencies,
-      packagesWithConsumedBuilders);
+    Level.FINE,
+    'The following packages contain builders that are auto-applied or referenced in "build.yaml"',
+    unusedDependencies,
+    packagesWithConsumedBuilders,
+  );
   unusedDependencies.removeAll(packagesWithConsumedBuilders);
 
   // Remove deps that provide executables, those are assumed to be used
-  final packagesWithExecutables = unusedDependencies.where((name) {
+  bool providesExecutable(String name) {
     final package = packageConfig[name];
-    final binDir = Directory(p.join(p.fromUri(package!.root), 'bin'));
+    if (package == null) return false;
+    final binDir = Directory(p.join(p.fromUri(package.root), 'bin'));
     if (!binDir.existsSync()) return false;
 
     // Search for executables, if found we assume they are used
     return binDir.listSync().any((entity) => entity.path.endsWith('.dart'));
-  }).toSet();
+  }
+
+  final packagesWithExecutables = {
+    for (final package in unusedDependencies)
+      if (providesExecutable(package)) package,
+  };
 
   final nonDevPackagesWithExecutables =
       packagesWithExecutables.where(pubspec.dependencies.containsKey).toSet();
@@ -319,7 +351,7 @@ Future<void> run() async {
       unusedDependencies,
       nonDevPackagesWithExecutables,
     );
-    exitCode = 1;
+    result = false;
   }
 
   logIntersection(
@@ -347,12 +379,13 @@ Future<void> run() async {
       'These packages may be unused, or you may be using assets from these packages:',
       unusedDependencies,
     );
-    exitCode = 1;
+    result = false;
   }
 
-  if (exitCode == 0) {
+  if (result) {
     logger.info(green.wrap('✓ No dependency issues found!'));
   }
+  return result && subResult;
 }
 
 /// Whether a dependency at [path] defines an auto applied builder.
diff --git a/lib/src/pubspec_config.dart b/lib/src/pubspec_config.dart
index 3b0aad1..f89ead5 100644
--- a/lib/src/pubspec_config.dart
+++ b/lib/src/pubspec_config.dart
@@ -30,7 +30,7 @@ class PubspecDepValidatorConfig {
 @JsonSerializable(
     anyMap: true,
     checked: true,
-    createToJson: false,
+    createToJson: true,
     fieldRename: FieldRename.snake)
 class DepValidatorConfig {
   @JsonKey(defaultValue: [])
@@ -55,4 +55,6 @@ class DepValidatorConfig {
       checkedYamlDecode(
           yamlContent, (m) => DepValidatorConfig.fromJson(m ?? {}),
           allowNull: true, sourceUrl: sourceUrl);
+
+  Map<String, dynamic> toJson() => _$DepValidatorConfigToJson(this);
 }
diff --git a/lib/src/pubspec_config.g.dart b/lib/src/pubspec_config.g.dart
index d2b7949..3ea887d 100644
--- a/lib/src/pubspec_config.g.dart
+++ b/lib/src/pubspec_config.g.dart
@@ -41,3 +41,10 @@ DepValidatorConfig _$DepValidatorConfigFromJson(Map json) => $checkedCreate(
       },
       fieldKeyMap: const {'allowPins': 'allow_pins'},
     );
+
+Map<String, dynamic> _$DepValidatorConfigToJson(DepValidatorConfig instance) =>
+    <String, dynamic>{
+      'exclude': instance.exclude,
+      'ignore': instance.ignore,
+      'allow_pins': instance.allowPins,
+    };
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index b83ee4a..6610243 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -93,7 +93,7 @@ Iterable<File> listFilesWithExtensionIn(
 /// Logs the given [message] at [level] and lists all of the given [dependencies].
 void log(Level level, String message, Iterable<String> dependencies) {
   final sortedDependencies = dependencies.toList()..sort();
-  var combined = [message, bulletItems(sortedDependencies), ''].join('\n');
+  var combined = [message, bulletItems(sortedDependencies)].join('\n');
   if (level >= Level.SEVERE) {
     combined = red.wrap(combined)!;
   } else if (level >= Level.WARNING) {
@@ -183,3 +183,19 @@ DependencyPinEvaluation inspectVersionForPins(VersionConstraint constraint) {
 
   return DependencyPinEvaluation.emptyPin;
 }
+
+/// Utilities for Pubspec objects.
+extension PubspecUtils on Pubspec {
+  /// Whether this package is the root of a Pub Workspace.
+  bool get isWorkspaceRoot => workspace != null;
+
+  /// Whether this package is a sub-package in a Pub Workspace.
+  bool get isInWorkspace => resolution == 'workspace';
+}
+
+/// Makes a glob object for the given path.
+///
+/// This function removes `./` paths and replaces all `\` with `/`.
+Glob makeGlob(String path) => Glob(
+      p.posix.normalize(path.replaceAll(r'\', '/')),
+    );
diff --git a/pubspec.yaml b/pubspec.yaml
index 9d6916e..bf815de 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: dependency_validator
-version: 4.1.2
+version: 5.0.0
 description: Checks for missing, under-promoted, over-promoted, and unused dependencies.
 homepage: https://github.com/Workiva/dependency_validator
 
 environment:
-  sdk: '>=2.19.0 <3.0.0'
+  sdk: '^3.0.0'
 
 dependencies:
   analyzer: '>=5.4.0 <7.0.0'
@@ -18,7 +18,7 @@ dependencies:
   package_config: ^2.0.0
   path: ^1.8.0
   pub_semver: ^2.0.0
-  pubspec_parse: ^1.0.0
+  pubspec_parse: ^1.5.0
   yaml: ^3.1.0
 
 dev_dependencies:
diff --git a/test/executable_test.dart b/test/executable_test.dart
index e9f8093..22c0fca 100644
--- a/test/executable_test.dart
+++ b/test/executable_test.dart
@@ -15,443 +15,257 @@
 @TestOn('vm')
 import 'dart:io';
 
+import 'package:dependency_validator/src/pubspec_config.dart';
 import 'package:io/io.dart';
 import 'package:test/test.dart';
 import 'package:test_descriptor/test_descriptor.dart' as d;
 
-/// `master` on build_config has a min sdk bound of dart 3.0.0.
-/// Since dependency_validator is still designed to be used on dart 2
-/// code, we still want to run unit tests using this older version
-///
-/// The following ref, is the last commit in build_config that allowed
-/// dart 2 as a dependency
-const buildConfigRef = 'e2c837b48bd3c4428cb40e2bc1a6cf47d45df8cc';
-
-ProcessResult checkProject(String projectPath,
-    {List<String> optionalArgs = const []}) {
-  final pubGetResult =
-      Process.runSync('dart', ['pub', 'get'], workingDirectory: projectPath);
-  if (pubGetResult.exitCode != 0) {
-    return pubGetResult;
-  }
-
-  final args = [
-    'run',
-    'dependency_validator',
-    // This makes it easier to print(result.stdout) for debugging tests
-    '--verbose',
-    ...optionalArgs,
-  ];
-
-  return Process.runSync('dart', args, workingDirectory: projectPath);
-}
-
-/// Removes indentation from `'''` string blocks.
-String unindent(String multilineString) {
-  var indent = RegExp(r'^( *)').firstMatch(multilineString)![1];
-  assert(indent != null && indent.isNotEmpty);
-  return multilineString.replaceAll('$indent', '');
-}
+import 'utils.dart';
 
 void main() {
   group('dependency_validator', () {
     late ProcessResult result;
 
-    setUp(() async {
-      // Create fake project that any test may use
-      final fakeProjectPubspec = unindent('''
-          name: fake_project
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dev_dependencies:
-            dependency_validator:
-              path: ${Directory.current.path}
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      final fakeProjectBuild = unindent('''
-          builders:
-            someBuilder:
-              import: "package:fake_project/builder.dart"
-              builder_factories: ["someBuilder"]
-              build_extensions: {".dart" : [".woot.g.dart"]}
-              auto_apply: none
-              build_to: cache
-          ''');
-
-      await d.dir('fake_project', [
-        d.dir('lib', [
-          d.file('fake.dart', 'bool fake = true;'),
-          d.file('builder.dart', 'bool fake = true;'),
-        ]),
-        d.file('pubspec.yaml', fakeProjectPubspec),
-        d.file('build.yaml', fakeProjectBuild),
-      ]).create();
-    });
-
     tearDown(() {
       printOnFailure(result.stdout);
       printOnFailure(result.stderr);
     });
 
     test('fails with incorrect usage', () async {
-      final pubspec = unindent('''
-          name: common_binaries
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dev_dependencies:
-            dependency_validator:
-              path: ${Directory.current.path}
-          ''');
-
-      await d.dir('common_binaries', [
-        d.dir('lib', [
-          d.file('fake.dart', 'bool fake = true;'),
-        ]),
-        d.file('pubspec.yaml', pubspec),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/common_binaries',
-          optionalArgs: ['-x', 'tool/wdesk_sdk']);
-
+      result = await checkProject(
+        args: ['-x', 'tool/wdesk_sdk'],
+      );
       expect(result.exitCode, ExitCode.usage.code);
     });
 
     group('fails when there are packages missing from the pubspec', () {
-      setUp(() async {
-        final pubspec = unindent('''
-            name: missing
-            version: 0.0.0
-            private: true
-            environment:
-              sdk: '>=2.12.0 <4.0.0'
-            dev_dependencies:
-              dependency_validator:
-                path: ${Directory.current.path}
-            dependency_overrides:
-              build_config:
-                git:
-                  url: https://github.com/dart-lang/build.git
-                  path: build_config
-                  ref: $buildConfigRef
-            ''');
-
-        await d.dir('missing', [
-          d.dir('lib', [
-            d.file('missing.dart', 'import \'package:yaml/yaml.dart\';'),
-            d.file('missing.scss', '@import \'package:somescsspackage/foo\';'),
-          ]),
-          d.file('pubspec.yaml', pubspec),
-        ]).create();
-      });
-
-      test('', () {
-        result = checkProject('${d.sandbox}/missing');
+      final project = [
+        d.dir('lib', [
+          d.file('missing.dart', 'import "package:yaml/yaml.dart";'),
+          d.file('missing.scss', '@import "package:some_scss_package/foo";'),
+        ]),
+      ];
 
-        expect(result.exitCode, equals(1));
+      test('', () async {
+        result = await checkProject(project: project);
+        expect(result.exitCode, 1);
         expect(
-            result.stderr,
-            contains(
-                'These packages are used in lib/ but are not dependencies:'));
+          result.stderr,
+          contains('These packages are used in lib/ but are not dependencies:'),
+        );
         expect(result.stderr, contains('yaml'));
-        expect(result.stderr, contains('somescsspackage'));
+        expect(result.stderr, contains('some_scss_package'));
       });
 
-      test('except when the lib directory is excluded', () async {
-        await d.dir('missing', [
-          d.file('dart_dependency_validator.yaml', unindent('''
-            exclude:
-              - 'lib/**'
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/missing');
-        expect(result.exitCode, equals(0));
+      final excludeLib = DepValidatorConfig(exclude: ['lib/**']);
+      final ignorePackages = DepValidatorConfig(
+        ignore: ['yaml', 'some_scss_package'],
+      );
+
+      test('except when lib is excluded', () async {
+        result = await checkProject(
+          project: project,
+          config: excludeLib,
+        );
+        expect(result.exitCode, 0);
         expect(result.stderr, isEmpty);
       });
 
-      test(
-          'except when the lib directory is excluded (deprecated pubspec method)',
-          () {
-        final dependencyValidatorSection = unindent('''
-            dependency_validator:
-              exclude:
-                - 'lib/**'
-            ''');
-
-        File('${d.sandbox}/missing/pubspec.yaml').writeAsStringSync(
-            dependencyValidatorSection,
-            mode: FileMode.append,
-            flush: true);
-
-        result = checkProject('${d.sandbox}/missing');
+      test('except when lib is excluded (deprecated pubspec method)', () async {
+        result = await checkProject(
+          project: project,
+          config: excludeLib,
+          embedConfigInPubspec: true,
+        );
 
         expect(result.exitCode, equals(0));
         expect(
-            result.stderr,
-            contains(
-                'Configuring dependency_validator in pubspec.yaml is deprecated'));
+          result.stderr,
+          contains(
+            'Configuring dependency_validator in pubspec.yaml is deprecated',
+          ),
+        );
       });
 
       test('except when they are ignored', () async {
-        await d.dir('missing', [
-          d.file('dart_dependency_validator.yaml', unindent('''
-            ignore:
-              - yaml
-              - somescsspackage
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/missing');
+        result = await checkProject(
+          project: project,
+          config: ignorePackages,
+        );
         expect(result.exitCode, 0);
       });
 
-      test('except when they are ignored (deprecated pubspec method)', () {
-        final dependencyValidatorSection = unindent('''
-            dependency_validator:
-              ignore:
-                - yaml
-                - somescsspackage
-            ''');
-
-        File('${d.sandbox}/missing/pubspec.yaml').writeAsStringSync(
-            dependencyValidatorSection,
-            mode: FileMode.append);
-
-        result = checkProject('${d.sandbox}/missing');
+      test('except when they are ignored (deprecated pubspec method)',
+          () async {
+        result = await checkProject(
+          project: project,
+          config: ignorePackages,
+          embedConfigInPubspec: true,
+        );
         expect(result.exitCode, 0);
       });
     });
 
     group('fails when there are over promoted packages', () {
-      setUp(() async {
-        final pubspec = unindent('''
-            name: over_promoted
-            version: 0.0.0
-            private: true
-            environment:
-              sdk: '>=2.12.0 <4.0.0'
-            dependencies:
-              path: any
-              yaml: any
-            dev_dependencies:
-              dependency_validator:
-                path: ${Directory.current.path}
-            dependency_overrides:
-              build_config:
-                git:
-                  url: https://github.com/dart-lang/build.git
-                  path: build_config
-                  ref: $buildConfigRef
-            ''');
-
-        await d.dir('over_promoted', [
-          d.dir('web', [
-            d.file('main.dart', 'import \'package:path/path.dart\';'),
-            d.file('over_promoted.scss', '@import \'package:yaml/foo\';'),
-          ]),
-          d.file('pubspec.yaml', pubspec),
-        ]).create();
-      });
-
-      test('', () {
-        result = checkProject('${d.sandbox}/over_promoted');
+      final project = [
+        d.dir('web', [
+          d.file('main.dart', 'import "package:path/path.dart";'),
+          d.file('over_promoted.scss', '@import "package:yaml/foo";'),
+        ]),
+      ];
+      final dependencies = {
+        "path": hostedAny,
+        "yaml": hostedAny,
+      };
+      final config = DepValidatorConfig(ignore: ['path', 'yaml']);
+
+      test('', () async {
+        result = await checkProject(
+          project: project,
+          dependencies: dependencies,
+        );
 
         expect(result.exitCode, 1);
         expect(
-            result.stderr,
-            contains(
-                'These packages are only used outside lib/ and should be downgraded to dev_dependencies:'));
+          result.stderr,
+          contains(
+            'These packages are only used outside lib/ and should be downgraded to dev_dependencies:',
+          ),
+        );
         expect(result.stderr, contains('path'));
         expect(result.stderr, contains('yaml'));
       });
 
       test('except when they are ignored', () async {
-        await d.dir('over_promoted', [
-          d.file('dart_dependency_validator.yaml', unindent('''
-            ignore:
-              - path
-              - yaml
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/over_promoted');
+        result = await checkProject(
+          project: project,
+          dependencies: dependencies,
+          config: config,
+        );
         expect(result.exitCode, 0);
       });
 
-      test('except when they are ignored (deprecated pubspec method)', () {
-        final dependencyValidatorSection = unindent('''
-            dependency_validator:
-              ignore:
-                - path
-                - yaml
-            ''');
-
-        File('${d.sandbox}/over_promoted/pubspec.yaml').writeAsStringSync(
-            dependencyValidatorSection,
-            mode: FileMode.append);
-
-        result = checkProject('${d.sandbox}/over_promoted');
+      test('except when they are ignored (deprecated pubspec method)',
+          () async {
+        result = await checkProject(
+          project: project,
+          dependencies: dependencies,
+          config: config,
+          embedConfigInPubspec: true,
+        );
         expect(result.exitCode, 0);
       });
     });
 
     group('fails when there are under promoted packages', () {
-      setUp(() async {
-        final pubspec = unindent('''
-            name: under_promoted
-            version: 0.0.0
-            private: true
-            environment:
-              sdk: '>=2.12.0 <4.0.0'
-            dev_dependencies:
-              logging: any
-              yaml: any
-              dependency_validator:
-                path: ${Directory.current.path}
-            dependency_overrides:
-              build_config:
-                git:
-                  url: https://github.com/dart-lang/build.git
-                  path: build_config
-                  ref: $buildConfigRef
-            ''');
-
-        await d.dir('under_promoted', [
-          d.dir('lib', [
-            d.file('under_promoted.dart',
-                'import \'package:logging/logging.dart\';'),
-            d.file('under_promoted.scss', '@import \'package:yaml/foo\';'),
-          ]),
-          d.file('pubspec.yaml', pubspec),
-        ]).create();
-      });
+      final devDependencies = {
+        "logging": hostedAny,
+        "yaml": hostedAny,
+      };
+
+      final project = [
+        d.dir('lib', [
+          d.file('main.dart', 'import "package:logging/logging.dart";'),
+          d.file('main.scss', '@import "package:yaml/foo";'),
+        ]),
+      ];
 
-      test('', () {
-        result = checkProject('${d.sandbox}/under_promoted');
+      final config = DepValidatorConfig(ignore: ['logging', 'yaml']);
 
+      test('', () async {
+        result = await checkProject(
+          project: project,
+          devDependencies: devDependencies,
+        );
         expect(result.exitCode, 1);
         expect(
-            result.stderr,
-            contains(
-                'These packages are used in lib/ and should be promoted to actual dependencies:'));
+          result.stderr,
+          contains(
+            'These packages are used in lib/ and should be promoted to actual dependencies:',
+          ),
+        );
         expect(result.stderr, contains('logging'));
         expect(result.stderr, contains('yaml'));
       });
 
       test('except when they are ignored', () async {
-        await d.dir('under_promoted', [
-          d.file('dart_dependency_validator.yaml', unindent('''
-            ignore:
-              - logging
-              - yaml
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/under_promoted');
+        result = await checkProject(
+          project: project,
+          devDependencies: devDependencies,
+          config: config,
+        );
         expect(result.exitCode, 0);
       });
 
-      test('except when they are ignored (deprecated pubspec method)', () {
-        final dependencyValidatorSection = unindent('''
-            dependency_validator:
-              ignore:
-                - logging
-                - yaml
-            ''');
-
-        File('${d.sandbox}/under_promoted/pubspec.yaml').writeAsStringSync(
-            dependencyValidatorSection,
-            mode: FileMode.append);
-
-        result = checkProject('${d.sandbox}/under_promoted');
+      test('except when they are ignored (deprecated pubspec method)',
+          () async {
+        result = await checkProject(
+          project: project,
+          devDependencies: devDependencies,
+          config: config,
+          embedConfigInPubspec: true,
+        );
         expect(result.exitCode, 0);
       });
     });
 
     group('fails when there are unused packages', () {
-      setUp(() async {
-        final unusedPubspec = unindent('''
-            name: unused
-            version: 0.0.0
-            private: true
-            environment:
-              sdk: '>=2.12.0 <4.0.0'
-            dev_dependencies:
-              fake_project:
-                path: ${d.sandbox}/fake_project
-              dependency_validator:
-                path: ${Directory.current.path}
-            dependency_overrides:
-              build_config:
-                git:
-                  url: https://github.com/dart-lang/build.git
-                  path: build_config
-                  ref: $buildConfigRef
-            ''');
-
-        await d.dir('unused', [
-          d.file('pubspec.yaml', unusedPubspec),
-        ]).create();
-      });
+      final devDependencies = {
+        'yaml': hostedAny,
+      };
+
+      final config = DepValidatorConfig(ignore: ['yaml']);
 
-      test('', () {
-        result = checkProject('${d.sandbox}/unused');
+      test('', () async {
+        result = await checkProject(
+          devDependencies: devDependencies,
+        );
 
         expect(result.exitCode, 1);
         expect(
-            result.stderr,
-            contains(
-                'These packages may be unused, or you may be using assets from these packages:'));
-        expect(result.stderr, contains('fake_project'));
+          result.stderr,
+          contains(
+            'These packages may be unused, or you may be using assets from these packages:',
+          ),
+        );
+        expect(result.stderr, contains('yaml'));
       });
 
       test('and import is commented out', () async {
-        await d.dir('unused', [
-          d.dir('lib', [
-            d.file('commented_out.dart',
-                '// import \'package:other_project/other.dart\';'), // commented out import
-          ]),
-          d.dir('test', [
-            d.file('valid.dart', 'import \'package:fake_project/fake.dart\';'),
-          ])
-        ]).create();
-        result = checkProject('${d.sandbox}/unused');
+        result = await checkProject(
+          devDependencies: devDependencies,
+          project: [
+            d.dir('lib', [
+              d.file(
+                'main.dart',
+                '// import "package:other_project/other.dart";',
+              ),
+            ]),
+            d.dir('test', [
+              d.file('valid.dart', 'import "package:yaml/fake.dart";'),
+            ])
+          ],
+        );
         expect(result.exitCode, 0);
         expect(result.stdout, contains('No dependency issues found!'));
       });
 
       test('except when they are ignored', () async {
-        await d.dir('unused', [
-          d.file('dart_dependency_validator.yaml', unindent('''
-            ignore:
-              - fake_project
-              - yaml
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/unused');
+        result = await checkProject(
+          devDependencies: devDependencies,
+          config: config,
+        );
         expect(result.exitCode, 0);
         expect(result.stdout, contains('No dependency issues found!'));
       });
 
-      test('except when they are ignored (deprecated pubspec method)', () {
-        final dependencyValidatorSection = unindent('''
-            dependency_validator:
-              ignore:
-                - fake_project
-                - yaml
-            ''');
-
-        File('${d.sandbox}/unused/pubspec.yaml').writeAsStringSync(
-            dependencyValidatorSection,
-            mode: FileMode.append);
-
-        result = checkProject('${d.sandbox}/unused');
+      test('except when they are ignored (deprecated pubspec method)',
+          () async {
+        result = await checkProject(
+          devDependencies: devDependencies,
+          config: config,
+          embedConfigInPubspec: true,
+        );
         expect(result.exitCode, 0);
         expect(result.stdout, contains('No dependency issues found!'));
       });
@@ -459,119 +273,68 @@ void main() {
 
     test('warns when the analyzer package is depended on but not used',
         () async {
-      final pubspec = unindent('''
-          name: analyzer_dep
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dependencies:
-            analyzer: any
-          dev_dependencies:
-            dependency_validator:
-              path: ${Directory.current.path}
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      await d.dir('project', [
-        d.dir('lib', [
-          d.file('analyzer_dep.dart', ''),
-        ]),
-        d.file('dart_dependency_validator.yaml', unindent('''
-          ignore:
-            - analyzer
-          ''')),
-        d.file('pubspec.yaml', pubspec),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/project');
-
+      result = await checkProject(
+        dependencies: {
+          "analyzer": hostedAny,
+        },
+        project: [
+          d.dir('lib', [
+            d.file('main.dart', ''),
+          ]),
+        ],
+        config: DepValidatorConfig(ignore: ['analyzer']),
+      );
       expect(result.exitCode, 0);
       expect(
-          result.stderr,
-          contains(
-              'You do not need to depend on `analyzer` to run the Dart analyzer.'));
+        result.stderr,
+        contains(
+          'You do not need to depend on `analyzer` to run the Dart analyzer.',
+        ),
+      );
     });
 
     test('passes when all dependencies are used and valid', () async {
-      final pubspec = unindent('''
-          name: valid
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dependencies:
-            logging: any
-            yaml: any
-            fake_project:
-              path: ${d.sandbox}/fake_project
-          dev_dependencies:
-            dependency_validator:
-              path: ${Directory.current.path}
-            pedantic: any
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      final validDotDart = ''
-          'import \'package:logging/logging.dart\';'
-          'import \'package:fake_project/fake.dart\';'
-          '// import \'package:does_not_exist/fake.dart\''; // commented out and unused
-
-      await d.dir('valid', [
-        d.dir('lib', [
-          d.file('valid.dart', validDotDart),
-          d.file('valid.scss', '@import \'package:yaml/foo\';'),
-        ]),
-        d.file('pubspec.yaml', pubspec),
-        d.file('analysis_options.yaml',
-            'include: package:pedantic/analysis_options.1.8.0.yaml'),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/valid');
+      result = await checkProject(
+        dependencies: {
+          "logging": hostedAny,
+          "yaml": hostedAny,
+        },
+        devDependencies: {
+          "pedantic": hostedAny,
+        },
+        project: [
+          d.dir('lib', [
+            d.file('main.dart', unindent('''
+              import 'package:logging/logging.dart';
+              import 'package:yaml/yaml.dart';
+              // import 'package:does_not_exist/fake.dart';
+            ''')),
+            d.file('main.scss', '@import "package:yaml/foo";'),
+          ]),
+          d.file(
+            'analysis_options.yaml',
+            'include: package:pedantic/analysis_options.1.8.0.yaml',
+          ),
+        ],
+      );
 
       expect(result.exitCode, 0);
       expect(result.stdout, contains('No dependency issues found!'));
     });
 
     test('passes when dependencies not used provide executables', () async {
-      final pubspec = unindent('''
-          name: common_binaries
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dev_dependencies:
-            build_runner: ^2.3.3
-            coverage: any
-            dart_style: ^2.3.2
-            dependency_validator:
-              path: ${Directory.current.path}
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      await d.dir('common_binaries', [
-        d.dir('lib', [
-          d.file('fake.dart', 'bool fake = true;'),
-        ]),
-        d.file('pubspec.yaml', pubspec),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/common_binaries');
+      result = await checkProject(
+        devDependencies: {
+          "build_runner": hostedCompatibleWith('2.3.3'),
+          'coverage': hostedAny,
+          'dart_style': hostedCompatibleWith('2.3.2'),
+        },
+        project: [
+          d.dir('lib', [
+            d.file('main.dart', 'book fake = true;'),
+          ]),
+        ],
+      );
 
       expect(result.exitCode, 0);
       expect(result.stdout, contains('No dependency issues found!'));
@@ -580,73 +343,43 @@ void main() {
     test(
         'fails when dependencies not used provide executables, but are not dev_dependencies',
         () async {
-      final pubspec = unindent('''
-          name: common_binaries
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dependencies:
-            build_runner: ^2.3.3
-            coverage: any
-            dart_style: ^2.3.2
-            dependency_validator:
-              path: ${Directory.current.path}
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      await d.dir('common_binaries', [
-        d.dir('lib', [
-          d.file('fake.dart', 'bool fake = true;'),
-        ]),
-        d.file('pubspec.yaml', pubspec),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/common_binaries');
+      result = await checkProject(
+        dependencies: {
+          "build_runner": hostedCompatibleWith('2.3.3'),
+          "coverage": hostedAny,
+          "dart_style": hostedCompatibleWith('2.3.2'),
+        },
+        project: [
+          d.dir('lib', [
+            d.file('main.dart', 'bool fake = true;'),
+          ]),
+        ],
+      );
 
       expect(result.exitCode, 1);
       expect(
-          result.stderr,
-          contains(
-              'The following packages contain executables, and are only used outside of lib/. These should be downgraded to dev_dependencies'));
+        result.stderr,
+        contains(
+          'The following packages contain executables, and are only used outside of lib/. These should be downgraded to dev_dependencies',
+        ),
+      );
     });
 
     test(
         'passes when dependencies are not imported but provide auto applied builders',
         () async {
-      final pubspec = unindent('''
-          name: common_binaries
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dev_dependencies:
-            build_test: ^2.0.1
-            build_vm_compilers: ^1.0.3
-            build_web_compilers: ^3.2.7
-            dependency_validator:
-              path: ${Directory.current.path}
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      await d.dir('common_binaries', [
-        d.dir('lib', [
-          d.file('fake.dart', 'bool fake = true;'),
-        ]),
-        d.file('pubspec.yaml', pubspec),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/common_binaries');
+      result = await checkProject(
+        devDependencies: {
+          'build_test': hostedCompatibleWith('2.0.1'),
+          'build_vm_compilers': hostedCompatibleWith('1.0.3'),
+          'build_web_compilers': hostedCompatibleWith('3.2.7'),
+        },
+        project: [
+          d.dir('lib', [
+            d.file('main.dart', 'book fake = true;'),
+          ]),
+        ],
+      );
 
       expect(result.exitCode, 0);
       expect(result.stdout, contains('No dependency issues found!'));
@@ -654,108 +387,68 @@ void main() {
 
     test('passes when dependencies are not imported but provide used builders',
         () async {
-      final pubspec = unindent('''
-          name: common_binaries
-          version: 0.0.0
-          private: true
-          environment:
-            sdk: '>=2.12.0 <4.0.0'
-          dev_dependencies:
-            fake_project:
-              path: ${d.sandbox}/fake_project
-            dependency_validator:
-              path: ${Directory.current.path}
-          dependency_overrides:
-            build_config:
-              git:
-                url: https://github.com/dart-lang/build.git
-                path: build_config
-                ref: $buildConfigRef
-          ''');
-
-      final build = unindent(r'''
-            targets:
-              $default:
-                builders:
-                  fake_project|someBuilder:
-                    options: {}
-            ''');
-
-      await d.dir('common_binaries', [
-        d.dir('lib', [
-          d.file('nope.dart', 'bool nope = true;'),
-        ]),
-        d.file('pubspec.yaml', pubspec),
-        d.file('build.yaml', build),
-      ]).create();
-
-      result = checkProject('${d.sandbox}/common_binaries');
+      result = await checkProject(
+        devDependencies: {
+          'yaml': hostedAny,
+        },
+        project: [
+          d.dir('lib', [
+            d.file('main.dart', 'bool fake = true;'),
+          ]),
+          d.file(
+            'build.yaml',
+            unindent(r'''
+              targets:
+                $default:
+                  builders:
+                    yaml|someBuilder:
+                      options: {}
+          '''),
+          ),
+        ],
+      );
 
       expect(result.exitCode, 0);
       expect(result.stdout, contains('No dependency issues found!'));
     });
 
     group('when a dependency is pinned', () {
-      setUp(() async {
-        final pubspec = unindent('''
-            name: dependency_pins
-            version: 0.0.0
-            private: true
-            environment:
-              sdk: '>=2.12.0 <4.0.0'
-            dependencies:
-              logging: 1.0.2
-            dev_dependencies:
-              dependency_validator:
-                path: ${Directory.current.path}
-            dependency_overrides:
-              build_config:
-                git:
-                  url: https://github.com/dart-lang/build.git
-                  path: build_config
-                  ref: $buildConfigRef
-            ''');
-
-        await d.dir('dependency_pins', [
-          d.file('pubspec.yaml', pubspec),
-        ]).create();
-      });
+      final dependencies = {
+        'logging': hostedPinned('1.0.2'),
+      };
+
+      final allowPins = DepValidatorConfig(allowPins: true);
+      final ignorePackage = DepValidatorConfig(ignore: ['logging']);
 
-      test('fails if pins are not ignored', () {
-        result = checkProject('${d.sandbox}/dependency_pins');
+      test('fails if pins are not ignored', () async {
+        result = await checkProject(dependencies: dependencies);
 
         expect(result.exitCode, 1);
         expect(
-            result.stderr,
-            contains(
-                'These packages are pinned in pubspec.yaml:\n  * logging'));
+          result.stderr,
+          contains('These packages are pinned in pubspec.yaml:\n  * logging'),
+        );
       });
 
       test('should not fails if package is pinned but pins allowed', () async {
-        await d.dir('dependency_pins', [
-          d.dir('lib', [
-            d.file('test.dart', unindent('''
-            import 'package:logging/logging.dart';
-            final log = Logger('ExampleLogger');
-            ''')),
-          ]),
-          d.file('dart_dependency_validator.yaml', unindent('''
-            allow_pins: true
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/dependency_pins');
+        result = await checkProject(
+          dependencies: dependencies,
+          config: allowPins,
+          project: [
+            d.dir('lib', [
+              d.file('main.dart', 'import "package:logging/logging.dart";'),
+            ]),
+          ],
+        );
         expect(result.exitCode, 0);
         expect(result.stdout, contains('No dependency issues found!'));
       });
 
       test('ignores infractions if the package is ignored', () async {
-        await d.dir('dependency_pins', [
-          d.file('dart_dependency_validator.yaml', unindent('''
-            ignore:
-              - logging
-            '''))
-        ]).create();
-        result = checkProject('${d.sandbox}/dependency_pins');
+        result = await checkProject(
+          dependencies: dependencies,
+          config: ignorePackage,
+        );
         expect(result.exitCode, 0);
         expect(result.stdout, contains('No dependency issues found!'));
       });
diff --git a/test/pubspec_to_json.dart b/test/pubspec_to_json.dart
new file mode 100644
index 0000000..3fdb7df
--- /dev/null
+++ b/test/pubspec_to_json.dart
@@ -0,0 +1,58 @@
+import "package:pubspec_parse/pubspec_parse.dart";
+
+extension<K, V> on Map<K, V> {
+  Iterable<(K, V)> get records sync* {
+    for (final entry in entries) {
+      yield (entry.key, entry.value);
+    }
+  }
+}
+
+typedef Json = Map<String, dynamic>;
+
+extension on Dependency {
+  Json toJson() => switch (this) {
+        SdkDependency(:final sdk, :final version) => {
+            "sdk": sdk,
+            "version": version.toString(),
+          },
+        HostedDependency(:final hosted, :final version) => {
+            if (hosted != null) "hosted": hosted.url.toString(),
+            "version": version.toString(),
+          },
+        GitDependency(:final url, :final ref, :final path) => {
+            "git": {
+              "url": url.toString(),
+              if (path != null) "ref": ref,
+              if (path != null) "path": path,
+            },
+          },
+        PathDependency(:final path) => {
+            "path": path.replaceAll(r'\', '/'),
+          },
+      };
+}
+
+/// An as-needed implementation of `Pubspec.toJson` for testing.
+///
+/// See: https://github.com/dart-lang/tools/issues/1801
+extension PubspecToJson on Pubspec {
+  Json toJson() => {
+        "name": name,
+        "environment": {
+          for (final (sdk, version) in environment.records)
+            sdk: version.toString(),
+        },
+        if (resolution != null) "resolution": resolution,
+        if (workspace != null) "workspace": workspace,
+        "dependencies": {
+          for (final (name, dependency) in dependencies.records)
+            name: dependency.toJson(),
+        },
+        "dev_dependencies": {
+          for (final (name, dependency) in devDependencies.records)
+            name: dependency.toJson(),
+        }
+        // ...
+      };
+}
diff --git a/test/utils.dart b/test/utils.dart
new file mode 100644
index 0000000..7e287de
--- /dev/null
+++ b/test/utils.dart
@@ -0,0 +1,120 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:dependency_validator/src/dependency_validator.dart';
+import 'package:dependency_validator/src/pubspec_config.dart';
+import 'package:logging/logging.dart';
+import 'package:pub_semver/pub_semver.dart';
+import 'package:pubspec_parse/pubspec_parse.dart';
+import 'package:test/test.dart';
+import 'package:test_descriptor/test_descriptor.dart' as d;
+
+export 'package:logging/logging.dart' show Level;
+
+import 'pubspec_to_json.dart';
+
+Future<ProcessResult> checkProject({
+  DepValidatorConfig? config,
+  Map<String, Dependency> dependencies = const {},
+  Map<String, Dependency> devDependencies = const {},
+  List<d.Descriptor> project = const [],
+  List<String> args = const [],
+  bool embedConfigInPubspec = false,
+}) async {
+  final pubspec = Pubspec(
+    'project',
+    environment: requireDart36,
+    dependencies: dependencies,
+    devDependencies: {
+      ...devDependencies,
+      'dependency_validator': PathDependency(Directory.current.absolute.path),
+    },
+  );
+  final pubspecJson = pubspec.toJson();
+  if (embedConfigInPubspec && config != null) {
+    pubspecJson['dependency_validator'] = config.toJson();
+  }
+  final dir = d.dir('project', [
+    ...project,
+    d.file('pubspec.yaml', jsonEncode(pubspecJson)),
+    if (config != null && !embedConfigInPubspec)
+      d.file('dart_dependency_validator.yaml', jsonEncode(config.toJson())),
+  ]);
+  await dir.create();
+  final path = '${d.sandbox}/project';
+  final commandArgs = ['run', 'dependency_validator', '--verbose', ...args];
+  return await Process.run('dart', commandArgs, workingDirectory: path);
+}
+
+Dependency hostedCompatibleWith(String version) => HostedDependency(
+      version: VersionConstraint.compatibleWith(Version.parse(version)),
+    );
+
+Dependency hostedPinned(String version) => HostedDependency(
+      version: Version.parse(version),
+    );
+
+final hostedAny = HostedDependency(version: VersionConstraint.any);
+
+/// Removes indentation from `'''` string blocks.
+String unindent(String multilineString) {
+  var indent = RegExp(r'^( *)').firstMatch(multilineString)![1];
+  assert(indent != null && indent.isNotEmpty);
+  return multilineString.replaceAll('$indent', '');
+}
+
+void initLogs() =>
+    Logger.root.onRecord.map((record) => record.message).listen(print);
+
+final requireDart36 = {
+  "sdk": VersionConstraint.compatibleWith(Version.parse('3.6.0')),
+};
+
+Future<void> checkWorkspace({
+  required Map<String, Dependency> workspaceDeps,
+  required Map<String, Dependency> subpackageDeps,
+  required List<d.Descriptor> workspace,
+  required List<d.Descriptor> subpackage,
+  DepValidatorConfig? workspaceConfig,
+  DepValidatorConfig? subpackageConfig,
+  Level logLevel = Level.OFF,
+  Matcher matcher = isTrue,
+}) async {
+  final workspacePubspec = Pubspec(
+    'workspace',
+    environment: requireDart36,
+    dependencies: workspaceDeps,
+    workspace: ['subpackage'],
+  );
+  final subpackagePubspec = Pubspec(
+    'subpackage',
+    environment: requireDart36,
+    dependencies: subpackageDeps,
+    resolution: 'workspace',
+  );
+  final dir = d.dir(
+    'workspace',
+    [
+      ...workspace,
+      d.file('pubspec.yaml', jsonEncode(workspacePubspec.toJson())),
+      if (workspaceConfig != null)
+        d.file(
+          'dart_dependency_validator.yaml',
+          jsonEncode(workspaceConfig.toJson()),
+        ),
+      d.dir('subpackage', [
+        ...subpackage,
+        d.file('pubspec.yaml', jsonEncode(subpackagePubspec.toJson())),
+        if (subpackageConfig != null)
+          d.file(
+            'dart_dependency_validator.yaml',
+            jsonEncode(subpackageConfig.toJson()),
+          ),
+      ]),
+    ],
+  );
+  await dir.create();
+  Logger.root.level = logLevel;
+  final result = await checkPackage(root: '${d.sandbox}/workspace');
+  expect(result, matcher);
+}
diff --git a/test/workspace_test.dart b/test/workspace_test.dart
new file mode 100644
index 0000000..69acd34
--- /dev/null
+++ b/test/workspace_test.dart
@@ -0,0 +1,149 @@
+import 'package:dependency_validator/src/pubspec_config.dart';
+import 'package:pub_semver/pub_semver.dart';
+import 'package:pubspec_parse/pubspec_parse.dart';
+import 'package:test/test.dart';
+import 'package:test_descriptor/test_descriptor.dart' as d;
+
+import 'utils.dart';
+
+final usesHttp = [
+  d.dir('lib', [
+    d.file('main.dart', 'import "package:http/http.dart";'),
+  ]),
+];
+
+final dependsOnHttp = {
+  'http': HostedDependency(
+    version: VersionConstraint.any,
+  ),
+};
+
+final usesMeta = [
+  d.dir('lib', [
+    d.file('main.dart', 'import "package:meta/meta.dart";'),
+  ]),
+];
+
+final dependsOnMeta = {
+  "meta": HostedDependency(version: VersionConstraint.any),
+};
+
+final excludeMain = DepValidatorConfig(
+  exclude: ['lib/main.dart'],
+);
+
+void main() => group('Workspaces', () {
+      initLogs();
+      test(
+          'works in the trivial case',
+          () => checkWorkspace(
+                workspaceDeps: {},
+                workspace: [],
+                subpackage: [],
+                subpackageDeps: {},
+              ));
+
+      test(
+          'works in a basic case',
+          () => checkWorkspace(
+                workspace: usesHttp,
+                workspaceDeps: dependsOnHttp,
+                subpackage: usesHttp,
+                subpackageDeps: dependsOnHttp,
+              ));
+
+      test(
+          'works when the packages have different dependencies',
+          () => checkWorkspace(
+                workspace: usesHttp,
+                workspaceDeps: dependsOnHttp,
+                subpackage: usesMeta,
+                subpackageDeps: dependsOnMeta,
+              ));
+
+      group('fails when the root has an issue', () {
+        test(
+            '(sub-package is okay)',
+            () => checkWorkspace(
+                  workspace: [],
+                  workspaceDeps: {},
+                  subpackage: usesHttp,
+                  subpackageDeps: dependsOnHttp,
+                ));
+
+        test(
+            'even when it shares a dependency with the subpackage',
+            () => checkWorkspace(
+                  workspaceDeps: dependsOnHttp,
+                  workspace: [],
+                  subpackageDeps: dependsOnHttp,
+                  subpackage: usesHttp,
+                  matcher: isFalse,
+                ));
+      });
+
+      group('fails when the subpackage has an issue', () {
+        test(
+            '(root is okay)',
+            () => checkWorkspace(
+                  workspace: usesHttp,
+                  workspaceDeps: dependsOnHttp,
+                  subpackage: [],
+                  subpackageDeps: {},
+                ));
+
+        test(
+            'even when it shares a dependency with the subpackage',
+            () => checkWorkspace(
+                  workspace: usesHttp,
+                  workspaceDeps: dependsOnHttp,
+                  subpackage: usesHttp,
+                  subpackageDeps: {},
+                  matcher: isFalse,
+                ));
+      });
+
+      group('handles configs', () {
+        test(
+            'at the root',
+            () => checkWorkspace(
+                  workspace: usesHttp,
+                  workspaceDeps: {},
+                  workspaceConfig: excludeMain,
+                  subpackage: [],
+                  subpackageDeps: {},
+                ));
+
+        test(
+            'and fails at root when config is in subpackage',
+            () => checkWorkspace(
+                  workspace: usesHttp,
+                  workspaceDeps: {},
+                  subpackage: [],
+                  subpackageDeps: {},
+                  subpackageConfig: excludeMain,
+                  matcher: isFalse,
+                ));
+
+        test(
+            'in a subpackage',
+            () => checkWorkspace(
+                  workspace: [],
+                  workspaceDeps: {},
+                  subpackage: usesHttp,
+                  subpackageDeps: {},
+                  subpackageConfig: excludeMain,
+                ));
+
+        test(
+            'and fails in subpackage when config is in root',
+            () => checkWorkspace(
+                  workspace: [],
+                  workspaceDeps: {},
+                  workspaceConfig: excludeMain,
+                  subpackage: usesHttp,
+                  subpackageDeps: {},
+                  matcher: isFalse,
+                ));
+      });
+    });