feat(jest): expose maxmaxWorkers property in jest config (projen#1675)

closes projen#1645 --- By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
FitX · Mar 10, 2022 · 5b9369c · 5b9369c
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diff --git a/docs/api/API.md b/docs/api/API.md
@@ -14645,6 +14645,7 @@ Name | Type | Description
 **haste**?🔹 | <code>[javascript.HasteConfig](#projen-javascript-hasteconfig)</code> | This will be used to configure the behavior of jest-haste-map, Jest's internal file crawler/cache system.<br/>__*Default*__: {}
 **injectGlobals**?🔹 | <code>boolean</code> | Insert Jest's globals (expect, test, describe, beforeEach etc.) into the global environment. If you set this to false, you should import from @jest/globals.<br/>__*Default*__: true
 **maxConcurrency**?🔹 | <code>number</code> | A number limiting the number of tests that are allowed to run at the same time when using test.concurrent. Any test above this limit will be queued and executed once a slot is released.<br/>__*Default*__: 5
+**maxWorkers**?🔹 | <code>string &#124; number</code> | Specifies the maximum number of workers the worker-pool will spawn for running tests.<br/>__*Default*__: the number of the cores available on your machine minus one for the main thread
 **moduleDirectories**?🔹 | <code>Array<string></code> | An array of directory names to be searched recursively up from the requiring module's location.<br/>__*Default*__: ["node_modules"]
 **moduleFileExtensions**?🔹 | <code>Array<string></code> | An array of file extensions your modules use.<br/>__*Default*__: ["js", "json", "jsx", "ts", "tsx", "node"]
 **moduleNameMapper**?🔹 | <code>Map<string, string &#124; Array<string>></code> | A map from regular expressions to module names or to arrays of module names that allow to stub out resources, like images or styles with a single module.<br/>__*Default*__: null

diff --git a/src/javascript/jest.ts b/src/javascript/jest.ts
@@ -157,6 +157,15 @@ export interface JestConfigOptions {
    */
   readonly maxConcurrency?: number;
 
+  /**
+   * Specifies the maximum number of workers the worker-pool will spawn for running tests. In single run mode,
+   * this defaults to the number of the cores available on your machine minus one for the main thread
+   * In watch mode, this defaults to half of the available cores on your machine.
+   * For environments with variable CPUs available, you can use percentage based configuration: "maxWorkers": "50%"
+   * @default - the number of the cores available on your machine minus one for the main thread
+   */
+  readonly maxWorkers?: number | string;
+
   /**
    * An array of directory names to be searched recursively up from the requiring module's location.
    * Setting this option will override the default, if you wish to still search node_modules for packages

diff --git a/test/jest.test.ts b/test/jest.test.ts
@@ -64,6 +64,7 @@ test("Node Project Jest With Options Configured", () => {
         automock: true,
         bail: 5,
         notify: false,
+        maxWorkers: 1,
       },
     },
   });
@@ -75,6 +76,7 @@ test("Node Project Jest With Options Configured", () => {
   expect(jest.automock).toEqual(true);
   expect(jest.bail).toEqual(5);
   expect(jest.notify).toEqual(false);
+  expect(jest.maxWorkers).toEqual(1);
 });
 
 test("Node Project Jest With Path Configured", () => {