Add tests

internal/pkg/conflictless/cli_test.go

@@ -113,6 +113,7 @@ func TestCLIHelp(t *testing.T) {
 		{"help check", []string{"help", "check"}, false},
 		{"help create", []string{"help", "create"}, false},
 		{"help generate", []string{"help", "generate"}, false},
+		{"help preview", []string{"help", "preview"}, false},
 		{"help unknown", []string{"help", "unknown"}, true},
 	} {
 		t.Run(testCase.description, func(t *testing.T) {

internal/pkg/conflictless/conflictless_test.go

@@ -1,15 +1,27 @@
 package conflictless_test
 
 import (
+	"bytes"
+	"io"
 	"os"
 	"testing"
 )
 
+type readWriteCapture struct {
+	original   *os.File
+	read       *os.File
+	write      *os.File
+	outChannel chan string
+}
+
 const (
 	mkdirFileMode = 0o755
 	writeFileMode = 0o644
 )
 
+//nolint:gochecknoglobals
+var stdoutCapture *readWriteCapture
+
 func writeDataToFile(t *testing.T, data []byte, file *os.File) {
 	t.Helper()
 
@@ -40,3 +52,46 @@ func createTempFile(t *testing.T, dir, pattern string) *os.File {
 
 	return file
 }
+
+func startStdoutCapture(t *testing.T) {
+	t.Helper()
+
+	stdoutCapture = new(readWriteCapture)
+	stdoutCapture.original = os.Stdout
+
+	read, write, _ := os.Pipe()
+	stdoutCapture.read = read
+	stdoutCapture.write = write
+
+	os.Stdout = stdoutCapture.write
+
+	stdoutCapture.outChannel = make(chan string)
+
+	go func() {
+		var buf bytes.Buffer
+
+		_, err := io.Copy(&buf, read)
+		if err != nil {
+			t.Error(err.Error())
+		}
+
+		stdoutCapture.outChannel <- buf.String()
+	}()
+}
+
+func stopStdoutCapture(t *testing.T) string {
+	t.Helper()
+
+	if stdoutCapture == nil {
+		t.Errorf("could not stop stdout capture because stdout capture wasn't initialized")
+	}
+
+	stdoutCapture.write.Close()
+	os.Stdout = stdoutCapture.original
+
+	output := <-stdoutCapture.outChannel
+
+	stdoutCapture = nil
+
+	return output
+}

internal/pkg/conflictless/generate_test.go

@@ -16,8 +16,6 @@ func TestGenerate(t *testing.T) {
 
 	defer os.RemoveAll(changesDir)
 
-	os.TempDir()
-
 	changesFile := createFile(t, changesDir, "test-generate.json")
 	defer os.Remove(changesFile.Name())
 
@@ -36,6 +34,7 @@ func TestGenerate(t *testing.T) {
 	cfg := new(conflictless.Config)
 	cfg.Flags.Directory = &changesDir
 	cfg.Flags.Bump = &flagValueBumpPatch
+	cfg.Flags.SkipVersionLinks = true
 	cfg.ChangelogFile = changelogFile.Name()
 	cfg.RepositoryConfigFile = gitConfigFile.Name()
 

internal/pkg/conflictless/preview_test.go

@@ -0,0 +1,50 @@
+package conflictless_test
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/ypjama/conflictless-keepachangelog/internal/pkg/conflictless"
+)
+
+func TestPreview(t *testing.T) {
+	t.Parallel()
+
+	changesDir, err := os.MkdirTemp(os.TempDir(), "changes")
+	assert.NoError(t, err)
+
+	defer os.RemoveAll(changesDir)
+
+	changesFile := createFile(t, changesDir, "test-preview.json")
+	defer os.Remove(changesFile.Name())
+
+	changelogFile := createTempFile(t, os.TempDir(), "test-preview-CHANGELOG.md")
+	defer os.Remove(changelogFile.Name())
+
+	gitConfigFile := createTempFile(t, os.TempDir(), "test-preview.gitconfig")
+	defer os.Remove(gitConfigFile.Name())
+
+	writeDataToFile(t, []byte(`{"added":["New major feature"]}`), changesFile)
+	writeDataToFile(t, []byte(changelogContent), changelogFile)
+	writeDataToFile(t, []byte(gitConfig), gitConfigFile)
+
+	flagValueBumpPatch := "major"
+
+	cfg := new(conflictless.Config)
+	cfg.Flags.Directory = &changesDir
+	cfg.Flags.Bump = &flagValueBumpPatch
+	cfg.Flags.SkipVersionLinks = true
+	cfg.ChangelogFile = changelogFile.Name()
+	cfg.RepositoryConfigFile = gitConfigFile.Name()
+
+	startStdoutCapture(t)
+
+	conflictless.Preview(cfg)
+
+	output := stopStdoutCapture(t)
+
+	assert.Contains(t, output, "```md\n")
+	assert.Contains(t, output, "## [2.0.0]")
+	assert.Contains(t, output, "### Added\n\n- New major feature\n")
+}