Snapshot flow 2 (#1150)

* Flow type jest-snapshot

Adds requisite type declarations and annotations to the jest-snapshot
modules. I’m not *at all* familiar with what this code is responsible
for, so I had to guess at a few types.

Open questions:

  - Is the new Jasmine type appropriate?
  - For SnapshotFile._content, can the value type be more specific?
  - Flow complains about Object.assign() if the 1st argument is a
literal that doesn’t contain all the keys trying to be assigned (see
getMatchers)

* Update some types.

packages/jest-snapshot/src/SnapshotFile.js

@@ -4,6 +4,8 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
  */
 'use strict';
 
@@ -13,15 +15,30 @@ const path = require('path');
 const prettyFormat = require('pretty-format');
 const SNAPSHOT_EXTENSION = 'snap';
 
-const ensureDirectoryExists = filePath => {
+import type {Path} from 'types/Config';
+
+export type SnapshotFileT = SnapshotFile;
+
+export type MatchResult = {
+  actual: string,
+  expected: string,
+  pass: boolean,
+};
+
+type SaveStatus = {
+  deleted: boolean,
+  saved: boolean,
+};
+
+const ensureDirectoryExists = (filePath: Path) => {
   try {
     createDirectory(path.join(path.dirname(filePath)));
   } catch (e) {}
 };
 
 const escape = string => string.replace(/\`/g, '\\`');
 
-const fileExists = filePath => {
+const fileExists = (filePath: Path): boolean => {
   try {
     return fs.statSync(filePath).isFile();
   } catch (e) {}
@@ -30,40 +47,45 @@ const fileExists = filePath => {
 
 class SnapshotFile {
 
-  constructor(filename) {
+  _content: {[key: string]: any};
+  _dirty: boolean;
+  _filename: Path;
+  _uncheckedKeys: Set;
+
+  constructor(filename: Path): void {
     this._filename = filename;
     this._dirty = false;
 
     this._content = Object.create(null);
     if (this.fileExists(filename)) {
       try {
-        Object.assign(this._content, require(filename));
+        Object.assign(this._content, require.call(null, filename));
       } catch (e) {}
     }
     this._uncheckedKeys = new Set(Object.keys(this._content));
   }
 
-  hasUncheckedKeys() {
+  hasUncheckedKeys(): boolean {
     return this._uncheckedKeys.size > 0;
   }
 
-  fileExists() {
+  fileExists(): boolean {
     return fileExists(this._filename);
   }
 
-  removeUncheckedKeys() {
+  removeUncheckedKeys(): void {
     if (this._uncheckedKeys.size) {
       this._dirty = true;
       this._uncheckedKeys.forEach(key => delete this._content[key]);
       this._uncheckedKeys.clear();
     }
   }
 
-  serialize(data) {
+  serialize(data: any): string {
     return prettyFormat(data);
   }
 
-  save(update) {
+  save(update: boolean): SaveStatus {
     const status = {
       deleted: false,
       saved: false,
@@ -92,15 +114,15 @@ class SnapshotFile {
     return status;
   }
 
-  has(key) {
+  has(key: string): boolean {
     return this._content[key] !== undefined;
   }
 
-  get(key) {
+  get(key: string): any {
     return this._content[key];
   }
 
-  matches(key, value) {
+  matches(key: string, value: any): MatchResult {
     this._uncheckedKeys.delete(key);
     const actual = this.serialize(value);
     const expected = this.get(key);
@@ -111,7 +133,7 @@ class SnapshotFile {
     };
   }
 
-  add(key, value) {
+  add(key: string, value: any): void {
     this._dirty = true;
     this._uncheckedKeys.delete(key);
     this._content[key] = this.serialize(value);
@@ -121,7 +143,7 @@ class SnapshotFile {
 
 module.exports = {
   SNAPSHOT_EXTENSION,
-  forFile(testPath) {
+  forFile(testPath: Path): SnapshotFile {
     const snapshotsPath = path.join(path.dirname(testPath), '__snapshots__');
 
     const snapshotFilename = path.join(

packages/jest-snapshot/src/SnapshotState.js

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+'use strict';
+
+import type {SnapshotFileT} from './SnapshotFile';
+
+export type SnapshotState = {
+  currentSpecName: string,
+  getCounter: (() => number),
+  incrementCounter: (() => number),
+  snapshot: SnapshotFileT,
+  added: number,
+  updated: number,
+  matched: number,
+  unmatched: number,
+};

packages/jest-snapshot/src/getMatchers.js

@@ -4,20 +4,37 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
  */
 'use strict';
 
 const JasmineFormatter = require('jest-util').JasmineFormatter;
 
-module.exports = (filePath, options, jasmine, snapshotState) => ({
-  toMatchSnapshot: (util, customEquality) => {
+import type {FailedAssertion} from 'types/TestResult';
+import type {Jasmine} from 'types/Jasmine';
+import type {Path} from 'types/Config';
+import type {SnapshotState} from './SnapshotState';
+
+type CompareResult = {
+  pass: boolean,
+  message: ?string,
+};
+
+module.exports = (
+  filePath: Path,
+  options: Object,
+  jasmine: Jasmine,
+  snapshotState: SnapshotState,
+) => ({
+  toMatchSnapshot: (util: any, customEquality: any) => {
     return {
       negativeCompare() {
         throw new Error(
           'Jest: `.not` can not be used with `.toMatchSnapshot()`.'
         );
       },
-      compare(actual, expected) {
+      compare(actual: any, expected: any): CompareResult {
         if (expected !== undefined) {
           throw new Error(
             'Jest: toMatchSnapshot() does not accept parameters.'
@@ -64,8 +81,12 @@ module.exports = (filePath, options, jasmine, snapshotState) => ({
             const matcherName = 'toMatchSnapshot';
             const formatter = new JasmineFormatter(jasmine, {global: {}}, {});
             formatter.addDiffableMatcher(matcherName);
+
             message = formatter
-              .formatMatchFailure(Object.assign({matcherName}, matches))
+              .formatMatchFailure(Object.assign(
+                ({matcherName}: FailedAssertion),
+                matches
+              ))
               .replace(
                 'toMatchSnapshot:',
                 'toMatchSnapshot #' + (callCount + 1) + ':'

packages/jest-util/src/JasmineFormatter.js

@@ -63,8 +63,10 @@ class JasmineFormatter {
   formatMatchFailure(result: FailedAssertion) {
     let message;
     if (this._diffableMatchers[result.matcherName]) {
-      const isNot =
-        'isNot' in result ? result.isNot : /not to /.test(result.message);
+      const isNot = !!('isNot' in result
+        ? result.isNot
+        : /not to /.test(result.message || '')
+      );
       message = this.formatDiffable(
         result.matcherName,
         isNot,
@@ -78,8 +80,9 @@ class JasmineFormatter {
     // error message & stack live on 'trace' field in jasmine 1.3
     const error = result.trace ? result.trace : result;
     if (!this._config.noStackTrace && error.stack) {
+      const errorMessage = error.message || '';
       message = error.stack
-        .replace(message, error.message)
+        .replace(message, errorMessage)
         .replace(/^.*Error:\s*/, '');
     }
     return message;

types/Jasmine.js

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ */
+'use strict';
+
+export type Jasmine = Object;

types/TestResult.js

@@ -18,11 +18,12 @@ type Error = {
 
 export type FailedAssertion = {
   matcherName: string,
-  message: string,
+  message?: string,
   trace?: Error,
-  actual: any,
-  expected: any,
-  isNot: boolean,
+  actual?: any,
+  pass?: boolean,
+  expected?: any,
+  isNot?: boolean,
 };
 
 export type Status = 'passed' | 'failed' | 'skipped' | 'pending';