[API Extractor] Add support for printing a diff of changed API reports in non-local builds.

apps/api-extractor/package.json

@@ -44,6 +44,7 @@
     "@rushstack/rig-package": "workspace:*",
     "@rushstack/terminal": "workspace:*",
     "@rushstack/ts-command-line": "workspace:*",
+    "diff": "~8.0.2",
     "lodash": "~4.17.15",
     "minimatch": "10.0.3",
     "resolve": "~1.22.1",

apps/api-extractor/src/api/ConsoleMessageId.ts

@@ -61,6 +61,12 @@ export enum ConsoleMessageId {
    */
   ApiReportNotCopied = 'console-api-report-not-copied',
 
+  /**
+   * Changes to the API report:
+   * ___
+   */
+  ApiReportDiff = 'console-api-report-diff',
+
   /**
    * "You have changed the public API signature for this project.  Updating ___"
    */

apps/api-extractor/src/api/Extractor.ts

@@ -11,7 +11,7 @@ import type { ApiPackage } from '@microsoft/api-extractor-model';
 import { TSDocConfigFile } from '@microsoft/tsdoc-config';
 import {
   FileSystem,
-  type NewlineKind,
+  NewlineKind,
   PackageJsonLookup,
   type IPackageJson,
   type INodePackageJson,
@@ -91,6 +91,15 @@ export interface IExtractorInvokeOptions {
    * the STDERR/STDOUT console.
    */
   messageCallback?: (message: ExtractorMessage) => void;
+
+  /**
+   * If true, then any differences between the actual and expected API reports will be
+   * printed on the console.
+   *
+   * @remarks
+   * The diff is not printed if the expected API report file has not been created yet.
+   */
+  printApiReportDiff?: boolean;
 }
 
 /**
@@ -192,36 +201,52 @@ export class Extractor {
    * Invoke API Extractor using an already prepared `ExtractorConfig` object.
    */
   public static invoke(extractorConfig: ExtractorConfig, options?: IExtractorInvokeOptions): ExtractorResult {
-    if (!options) {
-      options = {};
-    }
-
-    const localBuild: boolean = options.localBuild || false;
-
-    let compilerState: CompilerState | undefined;
-    if (options.compilerState) {
-      compilerState = options.compilerState;
-    } else {
-      compilerState = CompilerState.create(extractorConfig, options);
-    }
+    const {
+      packageFolder,
+      messages,
+      tsdocConfiguration,
+      tsdocConfigFile: { filePath: tsdocConfigFilePath, fileNotFound: tsdocConfigFileNotFound },
+      apiJsonFilePath,
+      newlineKind,
+      reportTempFolder,
+      reportFolder,
+      apiReportEnabled,
+      reportConfigs,
+      testMode,
+      rollupEnabled,
+      publicTrimmedFilePath,
+      alphaTrimmedFilePath,
+      betaTrimmedFilePath,
+      untrimmedFilePath,
+      tsdocMetadataEnabled,
+      tsdocMetadataFilePath
+    } = extractorConfig;
+    const {
+      localBuild = false,
+      compilerState = CompilerState.create(extractorConfig, options),
+      messageCallback,
+      showVerboseMessages = false,
+      showDiagnostics = false,
+      printApiReportDiff = false
+    } = options ?? {};
 
     const sourceMapper: SourceMapper = new SourceMapper();
 
     const messageRouter: MessageRouter = new MessageRouter({
-      workingPackageFolder: extractorConfig.packageFolder,
-      messageCallback: options.messageCallback,
-      messagesConfig: extractorConfig.messages || {},
-      showVerboseMessages: !!options.showVerboseMessages,
-      showDiagnostics: !!options.showDiagnostics,
-      tsdocConfiguration: extractorConfig.tsdocConfiguration,
+      workingPackageFolder: packageFolder,
+      messageCallback,
+      messagesConfig: messages || {},
+      showVerboseMessages,
+      showDiagnostics,
+      tsdocConfiguration,
       sourceMapper
     });
 
-    if (extractorConfig.tsdocConfigFile.filePath && !extractorConfig.tsdocConfigFile.fileNotFound) {
-      if (!Path.isEqual(extractorConfig.tsdocConfigFile.filePath, ExtractorConfig._tsdocBaseFilePath)) {
+    if (tsdocConfigFilePath && !tsdocConfigFileNotFound) {
+      if (!Path.isEqual(tsdocConfigFilePath, ExtractorConfig._tsdocBaseFilePath)) {
         messageRouter.logVerbose(
           ConsoleMessageId.UsingCustomTSDocConfig,
-          'Using custom TSDoc config from ' + extractorConfig.tsdocConfigFile.filePath
+          `Using custom TSDoc config from ${tsdocConfigFilePath}`
         );
       }
     }
@@ -243,9 +268,7 @@ export class Extractor {
 
       messageRouter.logDiagnosticHeader('TSDoc configuration');
       // Convert the TSDocConfiguration into a tsdoc.json representation
-      const combinedConfigFile: TSDocConfigFile = TSDocConfigFile.loadFromParser(
-        extractorConfig.tsdocConfiguration
-      );
+      const combinedConfigFile: TSDocConfigFile = TSDocConfigFile.loadFromParser(tsdocConfiguration);
       const serializedTSDocConfig: object = MessageRouter.buildJsonDumpObject(
         combinedConfigFile.saveToObject()
       );
@@ -273,17 +296,14 @@ export class Extractor {
     }
 
     if (modelBuilder.docModelEnabled) {
-      messageRouter.logVerbose(
-        ConsoleMessageId.WritingDocModelFile,
-        'Writing: ' + extractorConfig.apiJsonFilePath
-      );
-      apiPackage.saveToJsonFile(extractorConfig.apiJsonFilePath, {
+      messageRouter.logVerbose(ConsoleMessageId.WritingDocModelFile, `Writing: ${apiJsonFilePath}`);
+      apiPackage.saveToJsonFile(apiJsonFilePath, {
         toolPackage: Extractor.packageName,
         toolVersion: Extractor.version,
 
-        newlineConversion: extractorConfig.newlineKind,
+        newlineConversion: newlineKind,
         ensureFolderExists: true,
-        testMode: extractorConfig.testMode
+        testMode
       });
     }
 
@@ -292,53 +312,51 @@ export class Extractor {
         collector,
         extractorConfig,
         messageRouter,
-        extractorConfig.reportTempFolder,
-        extractorConfig.reportFolder,
+        reportTempFolder,
+        reportFolder,
         reportConfig,
-        localBuild
+        localBuild,
+        printApiReportDiff
       );
     }
 
     let anyReportChanged: boolean = false;
-    if (extractorConfig.apiReportEnabled) {
-      for (const reportConfig of extractorConfig.reportConfigs) {
+    if (apiReportEnabled) {
+      for (const reportConfig of reportConfigs) {
         anyReportChanged = writeApiReport(reportConfig) || anyReportChanged;
       }
     }
 
-    if (extractorConfig.rollupEnabled) {
+    if (rollupEnabled) {
       Extractor._generateRollupDtsFile(
         collector,
-        extractorConfig.publicTrimmedFilePath,
+        publicTrimmedFilePath,
         DtsRollupKind.PublicRelease,
-        extractorConfig.newlineKind
+        newlineKind
       );
       Extractor._generateRollupDtsFile(
         collector,
-        extractorConfig.alphaTrimmedFilePath,
+        alphaTrimmedFilePath,
         DtsRollupKind.AlphaRelease,
-        extractorConfig.newlineKind
+        newlineKind
       );
       Extractor._generateRollupDtsFile(
         collector,
-        extractorConfig.betaTrimmedFilePath,
+        betaTrimmedFilePath,
         DtsRollupKind.BetaRelease,
-        extractorConfig.newlineKind
+        newlineKind
       );
       Extractor._generateRollupDtsFile(
         collector,
-        extractorConfig.untrimmedFilePath,
+        untrimmedFilePath,
         DtsRollupKind.InternalRelease,
-        extractorConfig.newlineKind
+        newlineKind
       );
     }
 
-    if (extractorConfig.tsdocMetadataEnabled) {
+    if (tsdocMetadataEnabled) {
       // Write the tsdoc-metadata.json file for this project
-      PackageMetadataManager.writeTsdocMetadataFile(
-        extractorConfig.tsdocMetadataFilePath,
-        extractorConfig.newlineKind
-      );
+      PackageMetadataManager.writeTsdocMetadataFile(tsdocMetadataFilePath, newlineKind);
     }
 
     // Show all the messages that we collected during analysis
@@ -373,6 +391,7 @@ export class Extractor {
    * @param reportDirectoryPath - The path to the directory under which the existing report file is located, and to
    * which the new report will be written post-comparison.
    * @param reportConfig - API report configuration, including its file name and {@link ApiReportVariant}.
+   * @param printApiReportDiff - {@link IExtractorInvokeOptions.printApiReportDiff}
    *
    * @returns Whether or not the newly generated report differs from the existing report (if one exists).
    */
@@ -383,7 +402,8 @@ export class Extractor {
     reportTempDirectoryPath: string,
     reportDirectoryPath: string,
     reportConfig: IExtractorConfigApiReport,
-    localBuild: boolean
+    localBuild: boolean,
+    printApiReportDiff: boolean
   ): boolean {
     let apiReportChanged: boolean = false;
 
@@ -411,7 +431,9 @@ export class Extractor {
 
     // Compare it against the expected file
     if (FileSystem.exists(expectedApiReportPath)) {
-      const expectedApiReportContent: string = FileSystem.readFile(expectedApiReportPath);
+      const expectedApiReportContent: string = FileSystem.readFile(expectedApiReportPath, {
+        convertLineEndings: NewlineKind.Lf
+      });
 
       if (
         !ApiReportGenerator.areEquivalentApiFileContents(actualApiReportContent, expectedApiReportContent)
@@ -439,6 +461,26 @@ export class Extractor {
             convertLineEndings: extractorConfig.newlineKind
           });
         }
+
+        if (messageRouter.showVerboseMessages || printApiReportDiff) {
+          const Diff: typeof import('diff') = require('diff');
+          const patch: import('diff').StructuredPatch = Diff.structuredPatch(
+            expectedApiReportShortPath,
+            actualApiReportShortPath,
+            expectedApiReportContent,
+            actualApiReportContent
+          );
+          const logFunction:
+            | (typeof MessageRouter.prototype)['logWarning']
+            | (typeof MessageRouter.prototype)['logVerbose'] = printApiReportDiff
+            ? messageRouter.logWarning.bind(messageRouter)
+            : messageRouter.logVerbose.bind(messageRouter);
+
+          logFunction(
+            ConsoleMessageId.ApiReportDiff,
+            'Changes to the API report:\n\n' + Diff.formatPatch(patch)
+          );
+        }
       } else {
         messageRouter.logVerbose(
           ConsoleMessageId.ApiReportUnchanged,

apps/api-extractor/src/cli/RunAction.ts

@@ -24,10 +24,11 @@ import { ExtractorConfig, type IExtractorConfigPrepareOptions } from '../api/Ext
 
 export class RunAction extends CommandLineAction {
   private readonly _configFileParameter: CommandLineStringParameter;
-  private readonly _localParameter: CommandLineFlagParameter;
-  private readonly _verboseParameter: CommandLineFlagParameter;
+  private readonly _localFlag: CommandLineFlagParameter;
+  private readonly _verboseFlag: CommandLineFlagParameter;
   private readonly _diagnosticsParameter: CommandLineFlagParameter;
-  private readonly _typescriptCompilerFolder: CommandLineStringParameter;
+  private readonly _typescriptCompilerFolderParameter: CommandLineStringParameter;
+  private readonly _printApiReportDiffFlag: CommandLineFlagParameter;
 
   public constructor(parser: ApiExtractorCommandLine) {
     super({
@@ -43,7 +44,7 @@ export class RunAction extends CommandLineAction {
       description: `Use the specified ${ExtractorConfig.FILENAME} file path, rather than guessing its location`
     });
 
-    this._localParameter = this.defineFlagParameter({
+    this._localFlag = this.defineFlagParameter({
       parameterLongName: '--local',
       parameterShortName: '-l',
       description:
@@ -53,7 +54,7 @@ export class RunAction extends CommandLineAction {
         ' report file is automatically copied in a local build.'
     });
 
-    this._verboseParameter = this.defineFlagParameter({
+    this._verboseFlag = this.defineFlagParameter({
       parameterLongName: '--verbose',
       parameterShortName: '-v',
       description: 'Show additional informational messages in the output.'
@@ -66,7 +67,7 @@ export class RunAction extends CommandLineAction {
         '  This flag also enables the "--verbose" flag.'
     });
 
-    this._typescriptCompilerFolder = this.defineStringParameter({
+    this._typescriptCompilerFolderParameter = this.defineStringParameter({
       parameterLongName: '--typescript-compiler-folder',
       argumentName: 'PATH',
       description:
@@ -76,13 +77,21 @@ export class RunAction extends CommandLineAction {
         ' "--typescriptCompilerFolder" option to specify the folder path where you installed the TypeScript package,' +
         " and API Extractor's compiler will use those system typings instead."
     });
+
+    this._printApiReportDiffFlag = this.defineFlagParameter({
+      parameterLongName: '--print-api-report-diff',
+      description:
+        'If provided, then any differences between the actual and expected API reports will be ' +
+        'printed on the console. Note that the diff is not printed if the expected API report file has not been ' +
+        'created yet.'
+    });
   }
 
   protected override async onExecuteAsync(): Promise<void> {
     const lookup: PackageJsonLookup = new PackageJsonLookup();
     let configFilename: string;
 
-    let typescriptCompilerFolder: string | undefined = this._typescriptCompilerFolder.value;
+    let typescriptCompilerFolder: string | undefined = this._typescriptCompilerFolderParameter.value;
     if (typescriptCompilerFolder) {
       typescriptCompilerFolder = path.normalize(typescriptCompilerFolder);
 
@@ -93,17 +102,17 @@ export class RunAction extends CommandLineAction {
           : undefined;
         if (!typescriptCompilerPackageJson) {
           throw new Error(
-            `The path specified in the ${this._typescriptCompilerFolder.longName} parameter is not a package.`
+            `The path specified in the ${this._typescriptCompilerFolderParameter.longName} parameter is not a package.`
           );
         } else if (typescriptCompilerPackageJson.name !== 'typescript') {
           throw new Error(
-            `The path specified in the ${this._typescriptCompilerFolder.longName} parameter is not a TypeScript` +
+            `The path specified in the ${this._typescriptCompilerFolderParameter.longName} parameter is not a TypeScript` +
               ' compiler package.'
           );
         }
       } else {
         throw new Error(
-          `The path specified in the ${this._typescriptCompilerFolder.longName} parameter does not exist.`
+          `The path specified in the ${this._typescriptCompilerFolderParameter.longName} parameter does not exist.`
         );
       }
     }
@@ -136,10 +145,11 @@ export class RunAction extends CommandLineAction {
     }
 
     const extractorResult: ExtractorResult = Extractor.invoke(extractorConfig, {
-      localBuild: this._localParameter.value,
-      showVerboseMessages: this._verboseParameter.value,
+      localBuild: this._localFlag.value,
+      showVerboseMessages: this._verboseFlag.value,
       showDiagnostics: this._diagnosticsParameter.value,
-      typescriptCompilerFolder: typescriptCompilerFolder
+      typescriptCompilerFolder: typescriptCompilerFolder,
+      printApiReportDiff: this._printApiReportDiffFlag.value
     });
 
     if (extractorResult.succeeded) {

apps/api-extractor/src/collector/MessageRouter.ts

@@ -422,7 +422,7 @@ export class MessageRouter {
 
   /**
    * This returns all remaining messages that were flagged with `addToApiReportFile`, but which were not
-   * retreieved using `fetchAssociatedMessagesForReviewFile()`.
+   * retrieved using `fetchAssociatedMessagesForReviewFile()`.
    */
   public fetchUnassociatedMessagesForReviewFile(): ExtractorMessage[] {
     const messagesForApiReportFile: ExtractorMessage[] = [];