fix(testing): update maxWorkers jest builder option to support string…

… type

Jest supports both number and string args for the maxWorkers option, per their latest docs. This
updates the options for the jest builder to support both number and string types. Also updates the
docs accordingly.

ISSUES CLOSED: nrwl#2871

docs/angular/api-jest/builders/jest.md

@@ -94,7 +94,7 @@ Prints the test results in JSON. This mode will send all other test output and u
 
 Alias(es): w
 
-Type: `number`
+Type: `number | string`
 
 Specifies the maximum number of workers the worker-pool will spawn for running tests. This defaults to the number of the cores available on your machine. Useful for CI. (its usually best not to override this default) (https://jestjs.io/docs/en/cli#maxworkers-num)
 

docs/react/api-jest/builders/jest.md

@@ -95,7 +95,7 @@ Prints the test results in JSON. This mode will send all other test output and u
 
 Alias(es): w
 
-Type: `number`
+Type: `number | string`
 
 Specifies the maximum number of workers the worker-pool will spawn for running tests. This defaults to the number of the cores available on your machine. Useful for CI. (its usually best not to override this default) (https://jestjs.io/docs/en/cli#maxworkers-num)
 

packages/jest/src/builders/jest/jest.impl.spec.ts

@@ -246,6 +246,36 @@ describe('Jest Builder', () => {
       );
     });
 
+    it('should support passing string type for maxWorkers option to jestCLI', async () => {
+      const run = await architect.scheduleBuilder('@nrwl/jest:jest', {
+        jestConfig: './jest.config.js',
+        tsConfig: './tsconfig.test.json',
+        maxWorkers: "50%",
+      });
+      expect(await run.result).toEqual(
+        jasmine.objectContaining({
+          success: true,
+        })
+      );
+      expect(runCLI).toHaveBeenCalledWith(
+        {
+          _: [],
+          globals: JSON.stringify({
+            'ts-jest': {
+              tsConfig: '/root/tsconfig.test.json',
+              stringifyContentPathRegex: '\\.(html|svg)$',
+              astTransformers: [
+                'jest-preset-angular/build/InlineFilesTransformer',
+                'jest-preset-angular/build/StripStylesTransformer',
+              ],
+            },
+          }),
+          maxWorkers: 2,
+        },
+        ['/root/jest.config.js']
+      );
+    });
+
     it('should send the main to runCLI', async () => {
       const run = await architect.scheduleBuilder('@nrwl/jest:jest', {
         jestConfig: './jest.config.js',
@@ -272,6 +302,7 @@ describe('Jest Builder', () => {
             },
           }),
           setupFilesAfterEnv: ['/root/test-setup.ts'],
+          maxWorkers: "50%",
           testPathPattern: [],
           watch: false,
         },

packages/jest/src/builders/jest/schema.d.ts

@@ -14,7 +14,7 @@ export interface JestBuilderOptions extends JsonObject {
   clearCache?: boolean;
   findRelatedTests?: string;
   json?: boolean;
-  maxWorkers?: number;
+  maxWorkers?: number | string;
   onlyChanged?: boolean;
   outputFile?: string;
   passWithNoTests?: boolean;

packages/jest/src/builders/jest/schema.json

@@ -61,7 +61,10 @@
     "maxWorkers": {
       "alias": "w",
       "description": "Specifies the maximum number of workers the worker-pool will spawn for running tests. This defaults to the number of the cores available on your machine. Useful for CI. (its usually best not to override this default) (https://jestjs.io/docs/en/cli#maxworkers-num)",
-      "type": "number"
+      "oneOf": [
+        { "type": "number" },
+        { "type": "string" }
+      ]
     },
     "onlyChanged": {
       "alias": "o",