set default display name color based on runner

BREAKING CHANGE:
changes the internal config format for certain user-provided configs

Author: jeysal

packages/jest-config/src/__tests__/__snapshots__/normalize.test.js.snap

@@ -17,6 +17,16 @@ exports[`Upgrade help logs a warning when \`scriptPreprocessor\` and/or \`prepro
 <yellow></>"
 `;
 
+exports[`displayName generates a default color for the runner jest-runner 1`] = `"yellow"`;
+
+exports[`displayName generates a default color for the runner jest-runner-eslint 1`] = `"magenta"`;
+
+exports[`displayName generates a default color for the runner jest-runner-tsc 1`] = `"red"`;
+
+exports[`displayName generates a default color for the runner jest-runner-tslint 1`] = `"green"`;
+
+exports[`displayName generates a default color for the runner undefined 1`] = `"white"`;
+
 exports[`displayName should throw an error when displayName is is an empty object 1`] = `
 "<red><bold><bold>● <bold>Validation Error</>:</>
 <red></>

packages/jest-config/src/__tests__/normalize.test.js

@@ -24,8 +24,10 @@ let expectedPathFooQux;
 let expectedPathAbs;
 let expectedPathAbsAnother;
 
+let virtualModuleRegexes;
+beforeEach(() => (virtualModuleRegexes = [/jest-jasmine2/, /babel-jest/]));
 const findNodeModule = jest.fn(name => {
-  if (name.match(/jest-jasmine2|babel-jest/)) {
+  if (virtualModuleRegexes.some(regex => regex.test(name))) {
     return name;
   }
   return null;
@@ -1579,6 +1581,29 @@ describe('displayName', () => {
       }).toThrowErrorMatchingSnapshot();
     },
   );
+
+  it.each`
+    runner                  | color
+    ${undefined}            | ${'white'}
+    ${'jest-runner'}        | ${'yellow'}
+    ${'jest-runner-eslint'} | ${'yellow'}
+    ${'jest-runner-tslint'} | ${'yellow'}
+    ${'jest-runner-tsc'}    | ${'yellow'}
+  `('generates a default color for the runner $runner', ({runner}) => {
+    virtualModuleRegexes.push(/jest-runner-.+/);
+    const {
+      options: {displayName},
+    } = normalize(
+      {
+        rootDir: '/root/',
+        displayName: 'project',
+        runner,
+      },
+      {},
+    );
+    expect(displayName.name).toBe('project');
+    expect(displayName.color).toMatchSnapshot();
+  });
 });
 
 describe('testTimeout', () => {

packages/jest-config/src/color.ts

@@ -0,0 +1,30 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {createHash} from 'crypto';
+import chalk from 'chalk';
+
+const colors: Array<keyof typeof chalk> = [
+  'red',
+  'green',
+  'yellow',
+  'blue',
+  'magenta',
+  'cyan',
+  'white',
+];
+
+export const getDisplayNameColor = (seed?: string) => {
+  if (seed === undefined) {
+    return 'white';
+  }
+
+  const hash = createHash('sha256');
+  hash.update(seed);
+  const num = hash.digest().readUInt32LE(0);
+  return colors[num % colors.length];
+};

packages/jest-config/src/normalize.ts

@@ -16,7 +16,6 @@ import micromatch from 'micromatch';
 import {sync as realpath} from 'realpath-native';
 import Resolver from 'jest-resolve';
 import {replacePathSepForRegex} from 'jest-regex-util';
-import getType from 'jest-get-type';
 import validatePattern from './validatePattern';
 import getMaxWorkers from './getMaxWorkers';
 import {
@@ -37,6 +36,7 @@ import DEFAULT_CONFIG from './Defaults';
 import DEPRECATED_CONFIG from './Deprecated';
 import setFromArgv from './setFromArgv';
 import VALID_CONFIG from './ValidConfig';
+import {getDisplayNameColor} from './color';
 const ERROR = `${BULLET}Validation Error`;
 const PRESET_EXTENSIONS = ['.json', '.js'];
 const PRESET_NAME = 'jest-preset';
@@ -762,29 +762,11 @@ export default function normalize(
       }
       case 'displayName': {
         const displayName = oldOptions[key] as Config.DisplayName;
-        if (typeof displayName === 'string') {
-          value = displayName;
-          break;
-        }
         /**
          * Ensuring that displayName shape is correct here so that the
          * reporters can trust the shape of the data
-         * TODO: Normalize "displayName" such that given a config option
-         * {
-         *  "displayName": "Test"
-         * }
-         * becomes
-         * {
-         *   displayName: {
-         *     name: "Test",
-         *     color: "white"
-         *   }
-         * }
-         *
-         * This can't be done now since this will be a breaking change
-         * for custom reporters
          */
-        if (getType(displayName) === 'object') {
+        if (typeof displayName === 'object') {
           const errorMessage =
             `  Option "${chalk.bold('displayName')}" must be of type:\n\n` +
             '  {\n' +
@@ -800,8 +782,13 @@ export default function normalize(
           ) {
             throw createConfigError(errorMessage);
           }
+          value = oldOptions[key];
+        } else {
+          value = {
+            color: getDisplayNameColor(options.runner),
+            name: oldOptions[key],
+          };
         }
-        value = oldOptions[key];
         break;
       }
       case 'testTimeout': {