fix(internal/godocfx): make friendlyAPIName tolerant of missing packages (googleapis#14194)

friendlyAPIName was recently changed to return an empty string instead
of an error when a package or metadata is not found.

This matches the [old
behavior](https://github.com/googleapis/google-cloud-go/blob/ec656b96fed7ec1fd31ebeb7e9e68cb2ae1e2c79/internal/godocfx/parse.go#L689)
prior to when fixes were made to account for individual .json files.

Without this change, our tests for alloydbconn, cloudqlconn will fail
since they don't .repo-metadata.json files, and also don't live in this
repository. In addition, the auth library generation also fails. None of
these packages required a friendly API namer in the old behavior.

Author: hongalex

internal/godocfx/godocfx_test.go

@@ -309,17 +309,7 @@ func TestFriendlyAPIName(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	// 3. Malformed metadata
-	badDir := t.TempDir()
-	badSubDir := filepath.Join(badDir, "apiv1")
-	if err := os.MkdirAll(badSubDir, 0755); err != nil {
-		t.Fatal(err)
-	}
-	if err := os.WriteFile(filepath.Join(badSubDir, ".repo-metadata.json"), []byte("invalid json"), 0644); err != nil {
-		t.Fatal(err)
-	}
-
-	// 4. Submodule avoidance
+	// 3. Submodule avoidance
 	pubsubDir := t.TempDir()
 	pubsubV2Dir := filepath.Join(pubsubDir, "v2")
 	if err := os.MkdirAll(pubsubV2Dir, 0755); err != nil {
@@ -335,13 +325,16 @@ func TestFriendlyAPIName(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	namer := &friendlyAPINamer{}
+	namer := &friendlyAPINamer{
+		Fallbacks: map[string]string{
+			"cloud.google.com/go/pubsub": "PubSub API",
+		},
+	}
 
 	tests := []struct {
 		importPath string
 		module     *packages.Module
 		want       string
-		wantErr    bool
 	}{
 		{
 			importPath: "cloud.google.com/go/storage",
@@ -367,33 +360,28 @@ func TestFriendlyAPIName(t *testing.T) {
 			},
 			want: "Storage API v1",
 		},
-		{
-			importPath: "cloud.google.com/go/bad",
-			module: &packages.Module{
-				Path: "cloud.google.com/go/bad",
-				Dir:  badDir,
-			},
-			wantErr: true,
-		},
 		{
 			importPath: "cloud.google.com/go/pubsub",
 			module: &packages.Module{
 				Path: "cloud.google.com/go/pubsub",
 				Dir:  pubsubDir,
 			},
-			wantErr: true, // Should NOT find v2's metadata.
+			want: "PubSub API", // Should NOT find v2's metadata, should find fallback.
 		},
 		{
-			importPath: "not found",
-			module:     nil,
-			wantErr:    true,
+			importPath: "cloud.google.com/go/nonexistent",
+			module: &packages.Module{
+				Path: "cloud.google.com/go/nonexistent",
+				Dir:  t.TempDir(), // An empty dir with no metadata
+			},
+			want: "", // Should return empty string and no error
 		},
 	}
 
 	for _, test := range tests {
 		got, err := namer.friendlyAPIName(test.importPath, test.module)
-		if (err != nil) != test.wantErr {
-			t.Errorf("friendlyAPIName(%q) got err: %v, wantErr %v", test.importPath, err, test.wantErr)
+		if err != nil {
+			t.Errorf("friendlyAPIName(%q) got err: %v", test.importPath, err)
 			continue
 		}
 		if got != test.want {

internal/godocfx/parse.go

@@ -791,7 +791,7 @@ func (d *friendlyAPINamer) friendlyAPIName(importPath string, module *packages.M
 	}
 
 	if description == "" {
-		return "", fmt.Errorf("no description found for %q and no fallback provided", importPath)
+		return "", nil
 	}
 
 	if apiV := vNumberRE.FindString(importPath); apiV != "" {

internal/godocfx/testdata/golden/cloud.google.com/go/storage@v1.33.0/index.yml

@@ -131,7 +131,7 @@ items:
         }
         </pre>
         <p>Objects are listed lexicographically by name. To filter objects
-        lexicographically, <a href="#Query.StartOffset">Query.StartOffset</a> and/or <a href="#Query.EndOffset">Query.EndOffset</a> can be used:
+        lexicographically, [Query.StartOffset] and/or [Query.EndOffset] can be used:
         <pre class="prettyprint">query := &amp;storage.Query{
             Prefix: &quot;&quot;,
             StartOffset: &quot;bar/&quot;,  // Only list objects lexicographically &gt;= &quot;bar/&quot;