Function TestGenerateParallelWithMerge

codegen/generator/generate_merge_test.go:136–205

TestGenerateParallelWithMerge verifies that parallel file writing correctly handles file merging when multiple generators target the same path. This tests the interaction between mergeFilesByPath and parallel rendering.

(t *testing.T)

// handles file merging when multiple generators target the same path. This
// tests the interaction between mergeFilesByPath and parallel rendering.
func TestGenerateParallelWithMerge(t *testing.T) {
	t.Cleanup(func() { Generators = generators })

	// Three generators: first two merge to same path, third is separate.
	// This exercises both merging and parallel writing with NumCPU workers.
	Generators = func(cmd string) ([]Genfunc, error) {
		return []Genfunc{
			func(genpkg string, roots []eval.Root) ([]*codegen.File, error) {
				f1 := &codegen.File{Path: filepath.Join(codegen.Gendir, "types", "merged.go")}
				f1.SectionTemplates = []*codegen.SectionTemplate{
					codegen.Header("Types", "types", nil),
					{Name: "type1", Source: "type Type1 struct{}\n"},
				}
				return []*codegen.File{f1}, nil
			},
			func(genpkg string, roots []eval.Root) ([]*codegen.File, error) {
				f2 := &codegen.File{Path: filepath.Join(codegen.Gendir, "types", "merged.go")}
				f2.SectionTemplates = []*codegen.SectionTemplate{
					codegen.Header("Types", "types", nil),
					{Name: "type2", Source: "type Type2 struct{}\n"},
				}
				return []*codegen.File{f2}, nil
			},
			func(genpkg string, roots []eval.Root) ([]*codegen.File, error) {
				f3 := &codegen.File{Path: filepath.Join(codegen.Gendir, "types", "separate.go")}
				f3.SectionTemplates = []*codegen.SectionTemplate{
					codegen.Header("Types", "types", nil),
					{Name: "type3", Source: "type Type3 struct{}\n"},
				}
				return []*codegen.File{f3}, nil
			},
		}, nil
	}

	dir := t.TempDir()
	outputs, err := Generate(dir, "gen", false)
	if err != nil {
		t.Fatalf("Generate failed: %v", err)
	}
	outputs = assertVersionFile(t, dir, outputs)

	if len(outputs) != 2 {
		t.Fatalf("expected 2 output files, got %d", len(outputs))
	}

	// Verify merged file contains both types
	mergedPath := filepath.Join(dir, codegen.Gendir, "types", "merged.go")
	bs, err := os.ReadFile(mergedPath)
	if err != nil {
		t.Fatalf("failed reading merged file: %v", err)
	}
	content := string(bs)
	if !strings.Contains(content, "type Type1 struct{}") {
		t.Fatalf("merged file missing Type1:\n%s", content)
	}
	if !strings.Contains(content, "type Type2 struct{}") {
		t.Fatalf("merged file missing Type2:\n%s", content)
	}