fix: allow 'gts clean' to follow tsconfig.json dependency chain (#185)

src/util.ts

@@ -38,12 +38,77 @@ export function nop() {
 /**
  * Find the tsconfig.json, read it, and return parsed contents.
  * @param rootDir Directory where the tsconfig.json should be found.
+ * If the tsconfig.json file has an "extends" field hop down the dependency tree
+ * until it ends or a circular reference is found in which case an error will be
+ * thrown
  */
 export async function getTSConfig(
-    rootDir: string, customReadFilep?: ReadFileP): Promise<{}> {
-  const tsconfigPath = path.join(rootDir, 'tsconfig.json');
+    rootDir: string, customReadFilep?: ReadFileP): Promise<ConfigFile> {
   customReadFilep = customReadFilep || readFilep;
-  const json = await customReadFilep(tsconfigPath, 'utf8');
-  const contents = JSON.parse(json);
-  return contents;
+  const readArr = new Set();
+  return await getBase('tsconfig.json', customReadFilep, readArr, rootDir);
+}
+
+/**
+ * Recursively iterate through the dependency chain until we reach the end of
+ * the dependency chain or encounter a circular reference
+ * @param filePath Filepath of file currently being read
+ * @param customReadFilep The file reading function being used
+ * @param readFiles an array of the previously read files so we can check for
+ * circular references
+ * returns a ConfigFile object containing the data from all the dependencies
+ */
+async function getBase(
+    filePath: string, customReadFilep: ReadFileP, readFiles: Set<string>,
+    currentDir: string): Promise<ConfigFile> {
+  customReadFilep = customReadFilep || readFilep;
+
+  filePath = path.resolve(currentDir, filePath);
+
+  // An error is thrown if there is a circular reference as specified by the
+  // TypeScript doc
+  if (readFiles.has(filePath)) {
+    throw new Error(`Circular reference in ${filePath}`);
+  }
+  readFiles.add(filePath);
+  try {
+    const json = await customReadFilep(filePath, 'utf8');
+    let contents = JSON.parse(json);
+
+    if (contents.extends) {
+      const nextFile = await getBase(
+          contents.extends, customReadFilep, readFiles, path.dirname(filePath));
+      contents = combineTSConfig(nextFile, contents);
+    }
+
+    return contents;
+  } catch (err) {
+    throw new Error(`${filePath} Not Found`);
+  }
+}
+
+/**
+ * Takes in 2 config files
+ * @param base is loaded first
+ * @param inherited is then loaded and overwrites base
+ */
+function combineTSConfig(base: ConfigFile, inherited: ConfigFile): ConfigFile {
+  const result: ConfigFile = {compilerOptions: {}};
+
+  Object.assign(result, base, inherited);
+  Object.assign(
+      result.compilerOptions, base.compilerOptions, inherited.compilerOptions);
+  delete result.extends;
+  return result;
+}
+
+/**
+ * An interface containing the top level data fields present in Config Files
+ */
+export interface ConfigFile {
+  files?: string[];
+  compilerOptions?: {};
+  include?: string[];
+  exclude?: string[];
+  extends?: string[];
 }

test/test-util.ts

@@ -16,19 +16,128 @@
 import test from 'ava';
 import * as path from 'path';
 
-import {getTSConfig} from '../src/util';
+import {ConfigFile, getTSConfig} from '../src/util';
+
+/**
+ * Creates a fake promisified readFile function from a map
+ * @param myMap contains a filepath as the key and a ConfigFile object as the
+ * value.
+ * The returned function has the same interface as fs.readFile
+ */
+function createFakeReadFilep(myMap: Map<string, ConfigFile>) {
+  return (configPath: string) => {
+    const configFile = myMap.get(configPath);
+    if (configFile) {
+      return Promise.resolve(JSON.stringify(configFile));
+    } else {
+      return Promise.reject(`${configPath} Not Found`);
+    }
+  };
+}
 
 test('get should parse the correct tsconfig file', async t => {
   const FAKE_DIRECTORY = '/some/fake/directory';
-  const FAKE_CONFIG = {a: 'b'};
+  const FAKE_CONFIG1 = {files: ['b']};
+
   function fakeReadFilep(
       configPath: string, encoding: string): Promise<string> {
     t.is(configPath, path.join(FAKE_DIRECTORY, 'tsconfig.json'));
     t.is(encoding, 'utf8');
-    return Promise.resolve(JSON.stringify(FAKE_CONFIG));
+    return Promise.resolve(JSON.stringify(FAKE_CONFIG1));
   }
   const contents = await getTSConfig(FAKE_DIRECTORY, fakeReadFilep);
-  t.deepEqual(contents, FAKE_CONFIG);
+  t.deepEqual(contents, FAKE_CONFIG1);
 });
 
+test('should throw an error if it finds a circular reference', async t => {
+  const FAKE_DIRECTORY = '/some/fake/directory';
+  const FAKE_CONFIG1 = {files: ['b'], extends: 'FAKE_CONFIG2'};
+  const FAKE_CONFIG2 = {extends: 'FAKE_CONFIG3'};
+  const FAKE_CONFIG3 = {extends: 'tsconfig.json'};
+  const myMap = new Map();
+  myMap.set('/some/fake/directory/tsconfig.json', FAKE_CONFIG1);
+  myMap.set('/some/fake/directory/FAKE_CONFIG2', FAKE_CONFIG2);
+  myMap.set('/some/fake/directory/FAKE_CONFIG3', FAKE_CONFIG3);
+
+
+  await t.throws(
+      getTSConfig(FAKE_DIRECTORY, createFakeReadFilep(myMap)), Error,
+      'Circular Reference Detected');
+});
+
+test('should follow dependency chain caused by extends files', async t => {
+  const FAKE_DIRECTORY = '/some/fake/directory';
+  const FAKE_CONFIG1 = {
+    compilerOptions: {a: 'n'},
+    files: ['b'],
+    extends: 'FAKE_CONFIG2'
+  };
+  const FAKE_CONFIG2 = {include: ['/stuff/*'], extends: 'FAKE_CONFIG3'};
+  const FAKE_CONFIG3 = {exclude: ['doesnt/look/like/anything/to/me']};
+  const combinedConfig = {
+    compilerOptions: {a: 'n'},
+    files: ['b'],
+    include: ['/stuff/*'],
+    exclude: ['doesnt/look/like/anything/to/me']
+  };
+
+  const myMap = new Map();
+  myMap.set('/some/fake/directory/tsconfig.json', FAKE_CONFIG1);
+  myMap.set('/some/fake/directory/FAKE_CONFIG2', FAKE_CONFIG2);
+  myMap.set('/some/fake/directory/FAKE_CONFIG3', FAKE_CONFIG3);
+
+  const contents =
+      await getTSConfig(FAKE_DIRECTORY, createFakeReadFilep(myMap));
+  t.deepEqual(contents, combinedConfig);
+});
+
+test(
+    'when a file contains an extends field, the base file is loaded first then overridden by the inherited files',
+    async t => {
+      const FAKE_DIRECTORY = '/some/fake/directory';
+      const FAKE_CONFIG1 = {files: ['b'], extends: 'FAKE_CONFIG2'};
+      const FAKE_CONFIG2 = {files: ['c'], extends: 'FAKE_CONFIG3'};
+      const FAKE_CONFIG3 = {files: ['d']};
+      const combinedConfig = {compilerOptions: {}, files: ['b']};
+      const myMap = new Map();
+      myMap.set('/some/fake/directory/tsconfig.json', FAKE_CONFIG1);
+      myMap.set('/some/fake/directory/FAKE_CONFIG2', FAKE_CONFIG2);
+      myMap.set('/some/fake/directory/FAKE_CONFIG3', FAKE_CONFIG3);
+
+      const contents =
+          await getTSConfig(FAKE_DIRECTORY, createFakeReadFilep(myMap));
+      t.deepEqual(contents, combinedConfig);
+    });
+
+test(
+    'when reading a file, all filepaths should be relative to the config file currently being read',
+    async t => {
+      const FAKE_DIRECTORY = '/some/fake/directory';
+      const FAKE_CONFIG1 = {files: ['b'], extends: './foo/FAKE_CONFIG2'};
+      const FAKE_CONFIG2 = {include: ['c'], extends: './bar/FAKE_CONFIG3'};
+      const FAKE_CONFIG3 = {exclude: ['d']};
+      const combinedConfig =
+          {compilerOptions: {}, exclude: ['d'], files: ['b'], include: ['c']};
+      const myMap = new Map();
+      myMap.set('/some/fake/directory/tsconfig.json', FAKE_CONFIG1);
+      myMap.set('/some/fake/directory/foo/FAKE_CONFIG2', FAKE_CONFIG2);
+      myMap.set('/some/fake/directory/foo/bar/FAKE_CONFIG3', FAKE_CONFIG3);
+
+      const contents =
+          await getTSConfig(FAKE_DIRECTORY, createFakeReadFilep(myMap));
+      t.deepEqual(contents, combinedConfig);
+    });
+
+test(
+    'function throws an error when reading a file that does not exist',
+    async t => {
+      const FAKE_DIRECTORY = '/some/fake/directory';
+      const myMap = new Map();
+
+      await t.throws(
+          getTSConfig(FAKE_DIRECTORY, createFakeReadFilep(myMap)), Error,
+          `${FAKE_DIRECTORY}/tsconfig.json Not Found`);
+    });
+
+
 // TODO: test errors in readFile, JSON.parse.