feat: support tsconfig references

e2e/package.json

@@ -4,6 +4,7 @@
   "devDependencies": {
     "@formatjs/ts-transformer": "^3.13.31",
     "@testing-library/react": "^14.3.1",
+    "@types/jest": "^29.5.14",
     "@types/react": "^18.3.3",
     "@types/react-dom": "^18.3.5",
     "esbuild": "~0.24.2",

e2e/tsconfig-projects/jest-compiler-cjs.config.ts

@@ -0,0 +1,8 @@
+import { type JestConfigWithTsJest, TS_JS_TRANSFORM_PATTERN } from 'ts-jest'
+
+export default {
+  displayName: 'tsconfig-projects-compiler-cjs',
+  transform: {
+    [TS_JS_TRANSFORM_PATTERN]: 'ts-jest',
+  },
+} satisfies JestConfigWithTsJest

e2e/tsconfig-projects/jest-compiler-esm.config.ts

@@ -0,0 +1,14 @@
+import { type JestConfigWithTsJest, TS_JS_TRANSFORM_PATTERN } from 'ts-jest'
+
+export default {
+  displayName: 'tsconfig-projects-compiler-esm',
+  extensionsToTreatAsEsm: ['.ts'],
+  transform: {
+    [TS_JS_TRANSFORM_PATTERN]: [
+      'ts-jest',
+      {
+        useESM: true,
+      },
+    ],
+  },
+} satisfies JestConfigWithTsJest

e2e/tsconfig-projects/jest-transpiler-cjs.config.ts

@@ -0,0 +1,8 @@
+import { type JestConfigWithTsJest, TS_JS_TRANSFORM_PATTERN } from 'ts-jest'
+
+export default {
+  displayName: 'tsconfig-projects-transpiler-cjs',
+  transform: {
+    [TS_JS_TRANSFORM_PATTERN]: 'ts-jest',
+  },
+} satisfies JestConfigWithTsJest

e2e/tsconfig-projects/jest-transpiler-esm.config.ts

@@ -0,0 +1,14 @@
+import { type JestConfigWithTsJest, TS_JS_TRANSFORM_PATTERN } from 'ts-jest'
+
+export default {
+  displayName: 'tsconfig-projects-transpiler-esm',
+  extensionsToTreatAsEsm: ['.ts'],
+  transform: {
+    [TS_JS_TRANSFORM_PATTERN]: [
+      'ts-jest',
+      {
+        useESM: true,
+      },
+    ],
+  },
+} satisfies JestConfigWithTsJest

e2e/tsconfig-projects/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "tsconfig-projects",
+  "private": true
+}

e2e/tsconfig-projects/src/foo.spec.ts

@@ -0,0 +1,7 @@
+import { foo } from './foo'
+
+describe('foo', () => {
+  it('should return "foo"', () => {
+    expect(foo()).toEqual('foo')
+  })
+})

e2e/tsconfig-projects/src/foo.ts

@@ -0,0 +1,3 @@
+export function foo() {
+  return 'foo'
+}

e2e/tsconfig-projects/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.json",
+  "include": [],
+  "references": [
+    { "path": "./tsconfig.src.json" },
+    { "path": "./tsconfig.spec.json" }
+  ]
+}

e2e/tsconfig-projects/tsconfig.spec.json

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "module": "Node16",
+    "typeRoots": ["../node_modules"],
+    "types": ["@types/jest", "@types/node"],
+  },
+  "include": ["src/**/*.spec.ts"]
+}

e2e/tsconfig-projects/tsconfig.src.json

@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "Node16"
+  },
+  "include": ["src"],
+  "exclude": ["src/**/*.spec.ts"]
+}

src/legacy/config/config-set.spec.ts

@@ -790,7 +790,6 @@ describe('_resolveTsConfig', () => {
       expect(conf.options.configFilePath).toBeUndefined()
       expect(findConfig).not.toHaveBeenCalled()
       expect(readConfig.mock.calls[0][0]).toBe('/foo/tsconfig.bar.json')
-      expect(parseConfig).not.toHaveBeenCalled()
     })
   })
 
@@ -918,7 +917,6 @@ describe('_resolveTsConfig', () => {
 
         const conf = cs.parsedTsConfig
         expect(conf.options.path).toBe(tscfgPathStub)
-        expect(findConfig).not.toHaveBeenCalled()
         expect(readConfig.mock.calls[0][0]).toBe(tscfgPathStub)
         expect(parseConfig.mock.calls[0][2]).toBe('/foo')
         expect(parseConfig.mock.calls[0][4]).toBe(tscfgPathStub)

src/legacy/config/config-set.ts

@@ -202,8 +202,6 @@ export class ConfigSet {
 
     this.logger.debug({ compilerModule: this.compilerModule }, 'normalized compiler module config via ts-jest option')
 
-    this._setupConfigSet(options)
-    this._resolveTsCacheDir()
     this._matchablePatterns = [...this._jestCfg.testMatch, ...this._jestCfg.testRegex].filter(
       (pattern) =>
         /**
@@ -218,6 +216,9 @@ export class ConfigSet {
     this._matchTestFilePath = globsToMatcher(
       this._matchablePatterns.filter((pattern: string | RegExp) => typeof pattern === 'string') as string[],
     )
+
+    this._setupConfigSet(options)
+    this._resolveTsCacheDir()
   }
 
   /**
@@ -554,9 +555,7 @@ export class ConfigSet {
     let basePath = normalizeSlashes(this.rootDir)
     const ts = this.compilerModule
     // Read project configuration when available.
-    const configFileName: string | undefined = resolvedConfigFile
-      ? normalizeSlashes(resolvedConfigFile)
-      : ts.findConfigFile(normalizeSlashes(this.rootDir), ts.sys.fileExists)
+    const configFileName: string | undefined = this._findTsconfigFile(resolvedConfigFile)
     if (configFileName) {
       this.logger.debug({ tsConfigFileName: configFileName }, 'readTsConfig(): reading', configFileName)
 
@@ -576,6 +575,55 @@ export class ConfigSet {
     }
 
     // parse json, merge config extending others, ...
+    return this._parseTsconfig(config, basePath, configFileName)
+  }
+
+  protected _findTsconfigFile(resolvedConfigFile?: string) {
+    const ts = this.compilerModule
+
+    const configFileName: string | undefined = resolvedConfigFile
+      ? normalizeSlashes(resolvedConfigFile)
+      : ts.findConfigFile(normalizeSlashes(this.rootDir), ts.sys.fileExists)
+
+    const newTsconfigFile = this._findReferenceTsconfig(configFileName)
+
+    return newTsconfigFile ?? configFileName
+  }
+
+  protected _findReferenceTsconfig(tsconfigFileName?: string): string | undefined {
+    const ts = this.compilerModule
+
+    if (!tsconfigFileName) return
+
+    const parsedTsconfig = this._parseTsconfig(
+      ts.readConfigFile(tsconfigFileName, ts.sys.readFile).config || {},
+      dirname(tsconfigFileName),
+      tsconfigFileName,
+    )
+
+    if (this._includesTestFilesInConfig(parsedTsconfig)) return tsconfigFileName
+
+    if (parsedTsconfig.projectReferences) {
+      for (const ref of parsedTsconfig.projectReferences) {
+        const filePath = ts.resolveProjectReferencePath(ref)
+
+        if (ts.sys.fileExists(filePath)) {
+          const newTsconfigFileName = this._findReferenceTsconfig(ref.path)
+          if (newTsconfigFileName) return newTsconfigFileName
+        }
+      }
+    }
+
+    return
+  }
+
+  protected _includesTestFilesInConfig(parsedConfig?: ts.ParsedCommandLine) {
+    return parsedConfig?.fileNames?.length ? parsedConfig.fileNames.some((path) => this.isTestFile(path)) : false
+  }
+
+  protected _parseTsconfig(config: unknown, basePath: string, configFileName?: string) {
+    const ts = this.compilerModule
+
     return ts.parseJsonConfigFileContent(config, ts.sys, basePath, undefined, configFileName)
   }