feat(testing): add ability to split jest tests

package.json

@@ -206,6 +206,7 @@
     "jest-environment-jsdom": "29.4.3",
     "jest-environment-node": "^29.4.1",
     "jest-resolve": "^29.4.1",
+    "jest-runtime": "^29.4.1",
     "jest-util": "^29.4.1",
     "js-tokens": "^4.0.0",
     "js-yaml": "4.1.0",

packages/jest/src/plugins/plugin.spec.ts

@@ -24,7 +24,9 @@ describe('@nx/jest/plugin', () => {
     };
 
     await tempFs.createFiles({
-      'proj/jest.config.js': '',
+      'proj/jest.config.js': `module.exports = {}`,
+      'proj/src/unit.spec.ts': '',
+      'proj/src/ignore.spec.ts': '',
       'proj/project.json': '{}',
     });
   });
@@ -75,6 +77,90 @@ describe('@nx/jest/plugin', () => {
       }
     `);
   });
+
+  it('should create test-ci targets based on jest.config.ts', async () => {
+    mockJestConfig(
+      {
+        coverageDirectory: '../coverage',
+        testMatch: ['**/*.spec.ts'],
+        testPathIgnorePatterns: ['ignore.spec.ts'],
+      },
+      context
+    );
+    const nodes = await createNodesFunction(
+      'proj/jest.config.js',
+      {
+        targetName: 'test',
+        ciTargetName: 'test-ci',
+      },
+      context
+    );
+
+    expect(nodes.projects.proj).toMatchInlineSnapshot(`
+      {
+        "root": "proj",
+        "targets": {
+          "test": {
+            "cache": true,
+            "command": "jest",
+            "inputs": [
+              "default",
+              "^production",
+              {
+                "externalDependencies": [
+                  "jest",
+                ],
+              },
+            ],
+            "options": {
+              "cwd": "proj",
+            },
+            "outputs": [
+              "{workspaceRoot}/coverage",
+            ],
+          },
+          "test-ci": {
+            "cache": true,
+            "dependsOn": [
+              "test-ci--src/unit.spec.ts",
+            ],
+            "executor": "nx:noop",
+            "inputs": [
+              "default",
+              "^production",
+              {
+                "externalDependencies": [
+                  "jest",
+                ],
+              },
+            ],
+            "outputs": [
+              "{workspaceRoot}/coverage",
+            ],
+          },
+          "test-ci--src/unit.spec.ts": {
+            "cache": true,
+            "command": "jest src/unit.spec.ts",
+            "inputs": [
+              "default",
+              "^production",
+              {
+                "externalDependencies": [
+                  "jest",
+                ],
+              },
+            ],
+            "options": {
+              "cwd": "proj",
+            },
+            "outputs": [
+              "{workspaceRoot}/coverage",
+            ],
+          },
+        },
+      }
+    `);
+  });
 });
 
 function mockJestConfig(config: any, context: CreateNodesContext) {

packages/jest/src/plugins/plugin.ts

@@ -8,9 +8,8 @@ import {
   TargetConfiguration,
   writeJsonFile,
 } from '@nx/devkit';
-import { dirname, join, relative, resolve } from 'path';
+import { dirname, join, normalize, relative, resolve } from 'path';
 
-import { readTargetDefaultsForTarget } from 'nx/src/project-graph/utils/project-configuration-utils';
 import { getNamedInputs } from '@nx/devkit/src/utils/get-named-inputs';
 import { existsSync, readdirSync, readFileSync } from 'fs';
 import { readConfig } from 'jest-config';
@@ -22,6 +21,7 @@ import { minimatch } from 'minimatch';
 
 export interface JestPluginOptions {
   targetName?: string;
+  ciTargetName?: string;
 }
 
 const cachePath = join(projectGraphCacheDirectory, 'jest.hash');
@@ -127,12 +127,6 @@ async function buildJestTargets(
     resolve(context.workspaceRoot, configFilePath)
   );
 
-  const targetDefaults = readTargetDefaultsForTarget(
-    options.targetName,
-    context.nxJsonConfiguration.targetDefaults,
-    'nx:run-commands'
-  );
-
   const namedInputs = getNamedInputs(projectRoot, context);
 
   const targets: Record<string, TargetConfiguration> = {};
@@ -144,14 +138,57 @@ async function buildJestTargets(
     },
   });
 
-  if (!targetDefaults?.cache) {
-    target.cache = true;
-  }
-  if (!targetDefaults?.inputs) {
-    target.inputs = getInputs(namedInputs);
-  }
-  if (!targetDefaults?.outputs) {
-    target.outputs = getOutputs(projectRoot, config, context);
+  const cache = (target.cache = true);
+  const inputs = (target.inputs = getInputs(namedInputs));
+  const outputs = (target.outputs = getOutputs(projectRoot, config, context));
+
+  if (options?.ciTargetName) {
+    // Resolve the version of `jest-runtime` that `jest` is using.
+    const jestPath = require.resolve('jest');
+    const jest = require(jestPath) as typeof import('jest');
+    // nx-ignore-next-line
+    const { default: Runtime } = require(require.resolve('jest-runtime', {
+      paths: [dirname(jestPath)],
+      // nx-ignore-next-line
+    })) as typeof import('jest-runtime');
+
+    const context = await Runtime.createContext(config.projectConfig, {
+      maxWorkers: 1,
+      watchman: false,
+    });
+
+    const source = new jest.SearchSource(context);
+
+    const specs = await source.getTestPaths(config.globalConfig);
+
+    const testPaths = new Set(specs.tests.map(({ path }) => path));
+
+    if (testPaths.size > 0) {
+      const dependsOn: string[] = [];
+
+      targets[options.ciTargetName] = {
+        executor: 'nx:noop',
+        cache: true,
+        inputs,
+        outputs,
+        dependsOn,
+      };
+
+      for (const testPath of testPaths) {
+        const relativePath = normalize(relative(projectRoot, testPath));
+        const targetName = `${options.ciTargetName}--${relativePath}`;
+        dependsOn.push(targetName);
+        targets[targetName] = {
+          command: `jest ${relativePath}`,
+          cache,
+          inputs,
+          outputs,
+          options: {
+            cwd: projectRoot,
+          },
+        };
+      }
+    }
   }
 
   return targets;
@@ -200,6 +237,7 @@ function getOutputs(
 
   return outputs;
 }
+
 function normalizeOptions(options: JestPluginOptions): JestPluginOptions {
   options ??= {};
   options.targetName ??= 'test';