feat: add delete_generation_output_paths to repo-config.yaml

internal/librariangen/config/repoconfig.go

@@ -48,6 +48,11 @@ type ModuleConfig struct {
 	ModulePathVersion string `yaml:"module_path_version"`
 	// APIs is the list of APIs within this module (that need overrides).
 	APIs []*APIConfig `yaml:"apis"`
+	// DeleteGenerationOutputPaths specifies paths (files or directories) to
+	// be deleted from the output directory at the end of generation. This is for files
+	// which it is difficult to prevent from being generated, but which shouldn't appear
+	// in the repo.
+	DeleteGenerationOutputPaths []string `yaml:"delete_generation_output_paths"`
 }
 
 // APIConfig provides per-API configuration to override defaults,

internal/librariangen/generate/generator.go

@@ -132,6 +132,9 @@ func Generate(ctx context.Context, cfg *Config) error {
 			return fmt.Errorf("librariangen: post-processing failed: %w", err)
 		}
 	}
+	if err := deleteOutputPaths(cfg.OutputDir, moduleConfig.DeleteGenerationOutputPaths); err != nil {
+		return fmt.Errorf("librariangen: failed to delete paths specified in delete_generation_output_paths: %w", err)
+	}
 
 	slog.Debug("librariangen: generate command finished")
 	return nil
@@ -280,3 +283,20 @@ func moveFiles(sourceDir, targetDir string) error {
 	}
 	return nil
 }
+
+// deleteOutputPaths deletes the specified paths, which may be files
+// or directories, relative to the output directory. This is an emergency
+// escape hatch for situations where files are generated that we don't want
+// to include, such as the internal/generated/snippets/storage/internal directory.
+// This is configured in repo-config.yaml at the library level, with the key
+// delete_generation_output_paths.
+func deleteOutputPaths(outputDir string, pathsToDelete []string) error {
+	for _, path := range pathsToDelete {
+		// This is so rare that it's useful to be able to validate it easily.
+		slog.Info("deleting output path", "path", path)
+		if err := os.RemoveAll(filepath.Join(outputDir, path)); err != nil {
+			return err
+		}
+	}
+	return nil
+}

internal/librariangen/generate/generator_test.go

@@ -468,17 +468,50 @@ func TestApplyModuleVersion(t *testing.T) {
 			if tt.wantErr {
 				return
 			}
-
-			for _, wantPresent := range tt.wantPresent {
-				if _, err := os.Stat(filepath.Join(tmpDir, wantPresent)); err != nil {
-					t.Errorf("wanted present, was absent: %s", wantPresent)
-				}
-			}
-			for _, wantAbsent := range tt.wantAbsent {
-				if _, err := os.Stat(filepath.Join(tmpDir, wantAbsent)); !os.IsNotExist(err) {
-					t.Errorf("wanted absent, was missing: %s", wantAbsent)
-				}
-			}
+			assertPresent(t, tmpDir, tt.wantPresent)
+			assertAbsent(t, tmpDir, tt.wantAbsent)
 		})
 	}
 }
+
+func TestDeleteOutputPaths(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "apply-module-version-test")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	// We create file1, file2 and dir1/file3, then delete
+	// file1 and dir1; only file2 should be left.
+	if err := os.MkdirAll(filepath.Join(tmpDir, "dir1"), 0755); err != nil {
+		t.Fatalf("failed to create dir1: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(tmpDir, "file1"), []byte("test"), 0644); err != nil {
+		t.Fatalf("failed to write file1: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(tmpDir, "file2"), []byte("test"), 0644); err != nil {
+		t.Fatalf("failed to write file file2: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(tmpDir, "dir1", "file3"), []byte("test"), 0644); err != nil {
+		t.Fatalf("failed to write file dir1/file3: %v", err)
+	}
+	deleteOutputPaths(tmpDir, []string{"file1", "dir1"})
+	assertPresent(t, tmpDir, []string{"file2"})
+	assertAbsent(t, tmpDir, []string{"file1", "dir1"})
+}
+
+func assertPresent(t *testing.T, dir string, paths []string) {
+	t.Helper()
+	for _, path := range paths {
+		if _, err := os.Stat(filepath.Join(dir, path)); err != nil {
+			t.Errorf("wanted present, stat failed: %s", path)
+		}
+	}
+}
+
+func assertAbsent(t *testing.T, dir string, paths []string) {
+	t.Helper()
+	for _, path := range paths {
+		if _, err := os.Stat(filepath.Join(dir, path)); !os.IsNotExist(err) {
+			t.Errorf("wanted absent, was present (or stat failed): %s", path)
+		}
+	}
+}