feat(internal/librarian/python): bump snippet metadata versions (#4030)

Towards #3389

Author: jskeet

internal/librarian/python/bump.go

@@ -21,6 +21,8 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/googleapis/librarian/internal/snippetmetadata"
 )
 
 const (
@@ -37,7 +39,11 @@ var (
 // Bump updates the version number in the library with the given output
 // directory.
 func Bump(output, version string) error {
-	return bumpGapicVersions(output, version)
+	if err := bumpGapicVersions(output, version); err != nil {
+		return err
+	}
+	snippetsDir := filepath.Join(output, "samples", "generated_samples")
+	return snippetmetadata.UpdateAllLibraryVersions(snippetsDir, version)
 }
 
 // bumpGapicVersion finds all gapic_version.py files under output. For each

internal/librarian/python/bump_test.go

@@ -22,18 +22,34 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/googleapis/librarian/internal/snippetmetadata"
 )
 
 func TestBump(t *testing.T) {
 	const readme = "This is a readme file"
 	const versionBefore = "line1\n" + gapicVersionLinePrefix + "\"1.2.2\"# Other stuff\n" + "line3"
 	const versionAfter = "line1\n" + gapicVersionLinePrefix + "\"1.2.3\"\n" + "line3"
+	const snippetMetadataBefore = `{
+  "clientLibrary": {
+    "otherField": "x",
+    "version": "1.2.2"
+  },
+  "otherField": "y"
+}`
+	const snippetMetadataAfter = `{
+  "clientLibrary": {
+    "otherField": "x",
+    "version": "1.2.3"
+  },
+  "otherField": "y"
+}`
 	initial := map[string]string{
-		"README.txt":                              readme,
-		"docs/README.txt":                         readme,
-		"google/cloud/iam/" + gapicVersionFile:    versionBefore,
-		"google/cloud/iam_v1/" + gapicVersionFile: versionBefore,
-		"other/" + gapicVersionFile:               versionBefore,
+		"README.txt":                                      readme,
+		"docs/README.txt":                                 readme,
+		"google/cloud/iam/" + gapicVersionFile:            versionBefore,
+		"google/cloud/iam_v1/" + gapicVersionFile:         versionBefore,
+		"other/" + gapicVersionFile:                       versionBefore,
+		"samples/generated_samples/snippet_metadata.json": snippetMetadataBefore,
 	}
 	dir := t.TempDir()
 	for file, content := range initial {
@@ -51,11 +67,12 @@ func TestBump(t *testing.T) {
 	}
 
 	wantAfter := map[string]string{
-		"README.txt":                           readme,
-		"docs/README.txt":                      readme,
-		"google/cloud/iam/gapic_version.py":    versionAfter,
-		"google/cloud/iam_v1/gapic_version.py": versionAfter,
-		"other/gapic_version.py":               versionAfter,
+		"README.txt":                                      readme,
+		"docs/README.txt":                                 readme,
+		"google/cloud/iam/gapic_version.py":               versionAfter,
+		"google/cloud/iam_v1/gapic_version.py":            versionAfter,
+		"other/gapic_version.py":                          versionAfter,
+		"samples/generated_samples/snippet_metadata.json": snippetMetadataAfter,
 	}
 	for file, want := range wantAfter {
 		got, err := os.ReadFile(filepath.Join(dir, file))
@@ -95,6 +112,17 @@ func TestBump_Error(t *testing.T) {
 			},
 			wantErr: errNoVersionFound,
 		},
+		{
+			name: "snippet metadata file is invalid",
+			setup: func(dir string) error {
+				snippetMetadataPath := filepath.Join(dir, "samples", "generated_samples", "snippet_metadata.json")
+				if err := os.MkdirAll(filepath.Dir(snippetMetadataPath), 0755); err != nil {
+					t.Fatal(err)
+				}
+				return os.WriteFile(snippetMetadataPath, []byte("{}"), 0644)
+			},
+			wantErr: snippetmetadata.ErrNoClientLibraryField,
+		},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			dir := t.TempDir()
@@ -103,7 +131,7 @@ func TestBump_Error(t *testing.T) {
 			}
 			gotErr := Bump(dir, "1.2.3")
 			if !errors.Is(gotErr, test.wantErr) {
-				t.Errorf("bumpSingleGapicVersion() error = %v, wantErr %v", gotErr, test.wantErr)
+				t.Errorf("bump() error = %v, wantErr %v", gotErr, test.wantErr)
 			}
 		})
 	}

internal/snippetmetadata/snippetmetadata.go

@@ -26,7 +26,9 @@ import (
 )
 
 var (
-	errNoClientLibraryField     = errors.New("no clientLibrary field at the top level")
+	// ErrNoClientLibraryField is the error returned if a snippet metadata file
+	// has no clientLibrary field at the top level.
+	ErrNoClientLibraryField     = errors.New("no clientLibrary field at the top level")
 	errSnippetMetadataDirectory = errors.New("expected file; was a directory")
 	errSnippetMetadataLink      = errors.New("expected regular file; was a link")
 )
@@ -65,7 +67,7 @@ func updateLibraryVersion(path, version string) error {
 	}
 	clientLibrary, ok := metadata["clientLibrary"].(map[string]any)
 	if !ok {
-		return fmt.Errorf("error updating snippet metadata file %s: %w", path, errNoClientLibraryField)
+		return fmt.Errorf("error updating snippet metadata file %s: %w", path, ErrNoClientLibraryField)
 	}
 	clientLibrary["version"] = version
 	return writeMetadata(path, metadata)

internal/snippetmetadata/snippetmetadata_test.go

@@ -71,7 +71,7 @@ func TestUpdateLibraryVersion_Error(t *testing.T) {
 					t.Fatal(err)
 				}
 			},
-			wantErr: errNoClientLibraryField,
+			wantErr: ErrNoClientLibraryField,
 		},
 		{
 			name: "readonly file",