Adds enviroment structure to allow for thread safe unit testing

detect.go

@@ -1,16 +1,13 @@
 package gogenerate
 
 import (
-	"os"
-
 	"github.com/paketo-buildpacks/packit/v2"
 )
 
-func Detect() packit.DetectFunc {
+func Detect(generateEnvironement GenerateEnvironment) packit.DetectFunc {
 	return func(context packit.DetectContext) (packit.DetectResult, error) {
-		run := os.Getenv("BP_GO_GENERATE")
-		if run != "true" {
-			return packit.DetectResult{}, packit.Fail.WithMessage("BP_GO_GENERATE is empty")
+		if !generateEnvironement.RunGoGenerate {
+			return packit.DetectResult{}, packit.Fail.WithMessage("BP_GO_GENERATE is not truthy")
 		}
 
 		return packit.DetectResult{}, nil

detect_test.go

@@ -24,9 +24,9 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 		workingDir, err = os.MkdirTemp("", "working-dir")
 		Expect(err).NotTo(HaveOccurred())
 
-		os.Setenv("BP_GO_GENERATE", "true")
-
-		detect = gogenerate.Detect()
+		detect = gogenerate.Detect(gogenerate.GenerateEnvironment{
+			RunGoGenerate: true,
+		})
 	})
 
 	it.After(func() {
@@ -43,14 +43,16 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 
 	context("when BP_GO_GENERATE is empty", func() {
 		it.Before(func() {
-			os.Unsetenv("BP_GO_GENERATE")
+			detect = gogenerate.Detect(gogenerate.GenerateEnvironment{
+				RunGoGenerate: false,
+			})
 		})
 
 		it("fails detection", func() {
 			_, err := detect(packit.DetectContext{
 				WorkingDir: workingDir,
 			})
-			Expect(err).To(MatchError(packit.Fail.WithMessage("BP_GO_GENERATE is empty")))
+			Expect(err).To(MatchError(packit.Fail.WithMessage("BP_GO_GENERATE is not truthy")))
 		})
 	})
 }

environment.go

@@ -0,0 +1,7 @@
+package gogenerate
+
+type GenerateEnvironment struct {
+	RunGoGenerate   bool   `env:BP_GO_GENERATE`
+	GoGenerateArgs  string `env:BP_GO_GENERATE_ARGS`
+	GoGenerateFlags string `env:BP_GO_GENERATE_FLAGS`
+}

generate_configuration_parser.go

@@ -2,7 +2,6 @@ package gogenerate
 
 import (
 	"fmt"
-	"os"
 
 	"github.com/mattn/go-shellwords"
 )
@@ -13,10 +12,18 @@ type GenerateConfiguration struct {
 }
 
 type GenerateConfigurationParser struct {
+	generateEnvironment GenerateEnvironment
 }
 
-func NewGenerateConfigurationParser() GenerateConfigurationParser {
-	return GenerateConfigurationParser{}
+func NewGenerateConfigurationParser(generateEnvironment GenerateEnvironment) GenerateConfigurationParser {
+	return GenerateConfigurationParser{
+		generateEnvironment: generateEnvironment,
+	}
+}
+
+func (p GenerateConfigurationParser) WithEnvironment(generateEnvironment GenerateEnvironment) GenerateConfigurationParser {
+	p.generateEnvironment = generateEnvironment
+	return p
 }
 
 func (p GenerateConfigurationParser) Parse() (GenerateConfiguration, error) {
@@ -30,19 +37,19 @@ func (p GenerateConfigurationParser) Parse() (GenerateConfiguration, error) {
 	shellwordsParser.ParseEnv = true
 
 	generateConfiguration.Args = []string{"./..."}
-	if val, ok := os.LookupEnv("BP_GO_GENERATE_ARGS"); ok {
-		generateConfiguration.Args, err = shellwordsParser.Parse(val)
+	if p.generateEnvironment.GoGenerateArgs != "" {
+		generateConfiguration.Args, err = shellwordsParser.Parse(p.generateEnvironment.GoGenerateArgs)
 
 		if err != nil {
-			return GenerateConfiguration{}, fmt.Errorf("BP_GO_GENERATE_ARGS=%q: %w", val, err)
+			return GenerateConfiguration{}, fmt.Errorf("BP_GO_GENERATE_ARGS=%q: %w", p.generateEnvironment.GoGenerateArgs, err)
 		}
 	}
 
-	if val, ok := os.LookupEnv("BP_GO_GENERATE_FLAGS"); ok {
-		generateConfiguration.Flags, err = shellwordsParser.Parse(val)
+	if p.generateEnvironment.GoGenerateFlags != "" {
+		generateConfiguration.Flags, err = shellwordsParser.Parse(p.generateEnvironment.GoGenerateFlags)
 
 		if err != nil {
-			return GenerateConfiguration{}, fmt.Errorf("BP_GO_GENERATE_FLAGS=%q: %w", val, err)
+			return GenerateConfiguration{}, fmt.Errorf("BP_GO_GENERATE_FLAGS=%q: %w", p.generateEnvironment.GoGenerateFlags, err)
 		}
 	}
 	return generateConfiguration, nil

generate_configuration_parser_test.go

@@ -1,7 +1,6 @@
 package gogenerate_test
 
 import (
-	"os"
 	"testing"
 
 	gogenerate "github.com/paketo-buildpacks/go-generate"
@@ -18,16 +17,14 @@ func testGenerateConfigurationParser(t *testing.T, context spec.G, it spec.S) {
 	)
 
 	it.Before(func() {
-		parser = gogenerate.NewGenerateConfigurationParser()
+		parser = gogenerate.NewGenerateConfigurationParser(gogenerate.GenerateEnvironment{})
 	})
 
 	context("BP_GO_GENERATE_ARGS is set", func() {
 		it.Before(func() {
-			os.Setenv("BP_GO_GENERATE_ARGS", "somemodule othermodule")
-		})
-
-		it.After(func() {
-			os.Unsetenv("BP_GO_GENERATE_ARGS")
+			parser = parser.WithEnvironment(gogenerate.GenerateEnvironment{
+				GoGenerateArgs: "somemodule othermodule",
+			})
 		})
 
 		it("uses the values in the env var", func() {
@@ -37,7 +34,7 @@ func testGenerateConfigurationParser(t *testing.T, context spec.G, it spec.S) {
 				Args: []string{"somemodule", "othermodule"},
 			}))
 		})
-	}, spec.Sequential())
+	})
 
 	context("BP_GO_GENERATE_ARGS is NOT set", func() {
 		it("uses the default value", func() {
@@ -47,15 +44,13 @@ func testGenerateConfigurationParser(t *testing.T, context spec.G, it spec.S) {
 				Args: []string{"./..."},
 			}))
 		})
-	}, spec.Sequential())
+	})
 
 	context("BP_GO_GENERATE_FLAGS is set", func() {
 		it.Before(func() {
-			os.Setenv("BP_GO_GENERATE_FLAGS", `-run="^//go:generate go get" -n`)
-		})
-
-		it.After(func() {
-			os.Unsetenv("BP_GO_GENERATE_FLAGS")
+			parser = parser.WithEnvironment(gogenerate.GenerateEnvironment{
+				GoGenerateFlags: `-run="^//go:generate go get" -n`,
+			})
 		})
 
 		it("uses the values in the env var", func() {
@@ -66,38 +61,34 @@ func testGenerateConfigurationParser(t *testing.T, context spec.G, it spec.S) {
 				Flags: []string{`-run=^//go:generate go get`, "-n"},
 			}))
 		})
-	}, spec.Sequential())
+	})
 
 	context("failure cases", func() {
 
 		context("generate args fail to parse", func() {
 			it.Before(func() {
-				os.Setenv("BP_GO_GENERATE_ARGS", "\"")
+				parser = parser.WithEnvironment(gogenerate.GenerateEnvironment{
+					GoGenerateArgs: "\"",
+				})
 			})
 
 			it("returns an error", func() {
 				_, err := parser.Parse()
 				Expect(err).To(MatchError(ContainSubstring(`BP_GO_GENERATE_ARGS="\"": invalid command line string`)))
 			})
-
-			it.After(func() {
-				os.Unsetenv("BP_GO_GENERATE_ARGS")
-			})
-		}, spec.Sequential())
+		})
 
 		context("generate flags fail to parse", func() {
 			it.Before(func() {
-				os.Setenv("BP_GO_GENERATE_FLAGS", "\"")
+				parser = parser.WithEnvironment(gogenerate.GenerateEnvironment{
+					GoGenerateFlags: "\"",
+				})
 			})
 
 			it("returns an error", func() {
 				_, err := parser.Parse()
 				Expect(err).To(MatchError(ContainSubstring(`BP_GO_GENERATE_FLAGS="\"": invalid command line string`)))
 			})
-
-			it.After(func() {
-				os.Unsetenv("BP_GO_GENERATE_ARGS")
-			})
-		}, spec.Sequential())
+		})
 	})
 }

go.mod

@@ -18,6 +18,7 @@ require (
 	github.com/ForestEckhardt/freezer v0.1.0 // indirect
 	github.com/Masterminds/semver/v3 v3.2.1 // indirect
 	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/caarlos0/env/v6 v6.10.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
 	github.com/containerd/log v0.1.0 // indirect
 	github.com/containerd/platforms v0.2.1 // indirect

go.sum

@@ -1021,6 +1021,8 @@ github.com/butuzov/ireturn v0.1.1/go.mod h1:Wh6Zl3IMtTpaIKbmwzqi6olnM9ptYQxxVacM
 github.com/bwesterb/go-ristretto v1.2.0/go.mod h1:fUIoIZaG73pV5biE2Blr2xEzDoMj7NFEuV9ekS419A0=
 github.com/bytecodealliance/wasmtime-go v0.36.0/go.mod h1:q320gUxqyI8yB+ZqRuaJOEnGkAnHh6WtJjMaT2CW4wI=
 github.com/caarlos0/ctrlc v1.0.0/go.mod h1:CdXpj4rmq0q/1Eb44M9zi2nKB0QraNKuRGYGrrHhcQw=
+github.com/caarlos0/env/v6 v6.10.1 h1:t1mPSxNpei6M5yAeu1qtRdPAK29Nbcf/n3G7x+b3/II=
+github.com/caarlos0/env/v6 v6.10.1/go.mod h1:hvp/ryKXKipEkcuYjs9mI4bBCg+UI0Yhgm5Zu0ddvwc=
 github.com/campoy/unique v0.0.0-20180121183637-88950e537e7e/go.mod h1:9IOqJGCPMSc6E5ydlp5NIonxObaeu/Iub/X03EKPVYo=
 github.com/carolynvs/magex v0.9.0/go.mod h1:H1LW6RYJ/sNbisMmPe9E73aJZa8geKLKK9mBWLWz3ek=
 github.com/casbin/casbin/v2 v2.1.2/go.mod h1:YcPU1XXisHhLzuxH9coDNf2FbKpjGlbCg3n9yuLkIJQ=

run/main.go

@@ -1,8 +1,10 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
+	"github.com/caarlos0/env/v6"
 	gogenerate "github.com/paketo-buildpacks/go-generate"
 	"github.com/paketo-buildpacks/packit/v2"
 	"github.com/paketo-buildpacks/packit/v2/chronos"
@@ -13,10 +15,17 @@ import (
 func main() {
 	logger := scribe.NewLogger(os.Stdout)
 
+	var generateEnvironment gogenerate.GenerateEnvironment
+	err := env.Parse(&generateEnvironment)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, fmt.Errorf("failed to parse build configuration: %w", err))
+		os.Exit(1)
+	}
+
 	packit.Run(
-		gogenerate.Detect(),
+		gogenerate.Detect(generateEnvironment),
 		gogenerate.Build(
-			gogenerate.NewGenerateConfigurationParser(),
+			gogenerate.NewGenerateConfigurationParser(generateEnvironment),
 			gogenerate.NewGenerate(
 				pexec.NewExecutable("go"),
 				logger,