build(aio): improve error message for ignored example files (#19265)

Addresses https://github.com/angular/angular/pull/18707#issuecomment-330396771

PR Close #19265

aio/tools/transforms/angular-content-package/index.js

@@ -20,14 +20,25 @@ module.exports = new Package('angular-content', [basePackage, contentPackage])
   // Where do we get the source files?
   .config(function(readFilesProcessor, collectExamples) {
 
-    const gitignoreFile = fs.readFileSync(path.resolve(GUIDE_EXAMPLES_PATH, '.gitignore'), 'utf8');
+    const gitignoreFilePath = path.resolve(GUIDE_EXAMPLES_PATH, '.gitignore');
+    const gitignoreFile = fs.readFileSync(gitignoreFilePath, 'utf8');
     const gitignore = ignore().add(gitignoreFile);
 
     const examplePaths = glob.sync('**/*', { cwd: GUIDE_EXAMPLES_PATH, dot: true, ignore: '**/node_modules/**', mark: true })
                             .filter(filePath => filePath !== '.gitignore') // we are not interested in the .gitignore file itself
                             .filter(filePath => !/\/$/.test(filePath)); // this filter removes the folders, leaving only files
-    const filteredExamplePaths = gitignore.filter(examplePaths) // filter out files that match the .gitignore rules
+    const ignoredExamplePaths = [];
-                            .map(filePath => path.resolve(GUIDE_EXAMPLES_PATH, filePath)); // we need the full paths for the filereader
+    const resolvedExamplePaths = [];
+
+    examplePaths.forEach(filePath => {
+      // filter out files that match the .gitignore rules
+      if (gitignore.ignores(filePath)) {
+        ignoredExamplePaths.push(filePath);
+      } else {
+        // we need the full paths for the filereader
+        resolvedExamplePaths.push(path.resolve(GUIDE_EXAMPLES_PATH, filePath));
+      }
+    });
 
     readFilesProcessor.sourceFiles = readFilesProcessor.sourceFiles.concat([
       {
@@ -48,7 +59,7 @@ module.exports = new Package('angular-content', [basePackage, contentPackage])
       },
       {
         basePath: CONTENTS_PATH,
-        include: filteredExamplePaths,
+        include: resolvedExamplePaths,
         fileReader: 'exampleFileReader'
       },
       {
@@ -69,6 +80,7 @@ module.exports = new Package('angular-content', [basePackage, contentPackage])
     ]);
 
     collectExamples.exampleFolders.push('examples');
+    collectExamples.registerIgnoredExamples(ignoredExamplePaths, gitignoreFilePath);
   })
 
 

aio/tools/transforms/examples-package/processors/collect-examples.js

@@ -6,7 +6,26 @@ module.exports = function collectExamples(exampleMap, regionParser, log, createD
     $runAfter: ['files-read'],
     $runBefore: ['parsing-tags'],
     $validate: {exampleFolders: {presence: true}},
-    $process: function(docs) {
+    exampleFolders: [],
+    ignoredExamples: {},
+    /**
+     * Call this method to indicate to the processor that some files, that actually exist,
+     * have been filtered out from being processed.
+     * @param paths an array of relative paths to the examples that have been ignored.
+     * @param gitIgnorePath the path to the gitignore file that caused this example to be ignored.
+     */
+    registerIgnoredExamples(paths, gitIgnorePath) {
+      paths.forEach(path => { this.ignoredExamples[path] = gitIgnorePath; });
+    },
+    /**
+     * Call this method to find out if an example was ignored.
+     * @param path a relative path to the example file to test for being ignored.
+     * @returns the path to the .gitignore file.
+     */
+    isExampleIgnored(path) {
+      return this.ignoredExamples[path];
+    },
+    $process(docs) {
       const exampleFolders = this.exampleFolders;
       const regionDocs = [];
       docs = docs.filter((doc) => {

aio/tools/transforms/examples-package/processors/collect-examples.spec.js

@@ -23,6 +23,8 @@ describe('collectExampleRegions processor', () => {
     processor.exampleFolders = ['examples-1', 'examples-2'];
   });
 
+  describe('$process', () => {
+
     it('should identify example files that are in the exampleFolders', () => {
       const docs = [
         createDoc('A', 'examples-1/x/app.js'), createDoc('B', 'examples-1/y/index.html'),
@@ -182,6 +184,18 @@ describe('collectExampleRegions processor', () => {
     });
   });
 
+  describe('filtered examples', () => {
+    it('should indicate if an example was filtered', () => {
+      processor.registerIgnoredExamples(['c/d/e', 'e/f/g'], 'path/to/gitignore');
+      processor.registerIgnoredExamples(['x/y/z'], 'path/to/other/gitignore');
+      expect(processor.isExampleIgnored('a/b/c')).toBeFalsy();
+      expect(processor.isExampleIgnored('c/d/e')).toEqual('path/to/gitignore');
+      expect(processor.isExampleIgnored('e/f/g')).toEqual('path/to/gitignore');
+      expect(processor.isExampleIgnored('x/y/z')).toEqual('path/to/other/gitignore');
+    });
+  });
+});
+
 
 function createDoc(content, relativePath, docType) {
   return {

aio/tools/transforms/examples-package/services/getExampleRegion.js

@@ -14,15 +14,22 @@ module.exports = function getExampleRegion(exampleMap, createDocMessage, collect
 
     // If still no file then we error
     if (!exampleFile) {
-      const message = createDocMessage('Missing example file... relativePath: "' + relativePath + '".', doc) + '\n' +
+      const gitIgnoreFile = collectExamples.isExampleIgnored(relativePath);
-                      'Example files can be found in: ' + EXAMPLES_FOLDERS.join(', ');
+      if( gitIgnoreFile) {
+        const message = createDocMessage('Ignored example file... relativePath: "' + relativePath + '"', doc) + '\n' +
+        'This example file exists but has been ignored by a rule, in "' + gitIgnoreFile + '".';
         throw new Error(message);
+      } else {
+        const message = createDocMessage('Missing example file... relativePath: "' + relativePath + '".', doc) + '\n' +
+            'Example files can be found in the following relative paths: ' + EXAMPLES_FOLDERS.map(function(folder) { return '"' + folder + '"'; }).join(', ');
+        throw new Error(message);
+      }
     }
 
     var sourceCodeDoc = exampleFile.regions[regionName || ''];
     if (!sourceCodeDoc) {
       const message = createDocMessage('Missing example region... relativePath: "' + relativePath + '", region: "' + regionName + '".', doc) + '\n' +
-                      'Regions available are:' + Object.keys[exampleFile.regions];
+                      'Regions available are: ' + Object.keys(exampleFile.regions).map(function(region) { return '"' + region + '"'; }).join(', ');
       throw new Error(message);
     }
 

aio/tools/transforms/examples-package/services/getExampleRegion.spec.js

@@ -11,6 +11,7 @@ describe('getExampleRegion', () => {
     collectExamples = injector.get('collectExamples');
     exampleMap = injector.get('exampleMap');
     collectExamples.exampleFolders = ['examples'];
+    collectExamples.registerIgnoredExamples(['filtered/path'], 'some/gitignore');
     exampleMap['examples'] = {
       'test/url': { regions: {
         '': { renderedContent: 'whole file' },
@@ -27,12 +28,19 @@ describe('getExampleRegion', () => {
     expect(getExampleRegion({}, 'test/url', 'region-1')).toEqual('region 1 contents');
   });
 
-  it('should throw an error if an example doesn\'t exist', function() {
+  it('should throw an error if an example doesn\'t exist', () => {
-    expect(function() {
+    expect(() => {
       getExampleRegion({}, 'missing/file', 'region-1');
-    }).toThrowError();
+    }).toThrowError('Missing example file... relativePath: "missing/file". - doc\nExample files can be found in the following relative paths: "examples"');
-    expect(function() {
+    expect(() => {
       getExampleRegion({}, 'test/url', 'missing-region');
-    }).toThrowError();
+    }).toThrowError('Missing example region... relativePath: "test/url", region: "missing-region". - doc\nRegions available are: "", "region-1"');
+  });
+
+  it('should throw an error if an example has been filtered out', () => {
+    expect(() => {
+      getExampleRegion({}, 'filtered/path', 'any-region');
+    }).toThrowError('Ignored example file... relativePath: "filtered/path" - doc\n' +
+                    'This example file exists but has been ignored by a rule, in "some/gitignore".');
   });
 });