feat(config): allow to override readTsConfig

- Change `_readTsConfig` to `_resolveTsConfig`
- Allow to override `_resolveTsConfig` via overload signature
- Expose `_transformCfgStr`, `_configSet`, `_overriddenCompilerOptions`

src/compiler/language-service.ts

@@ -75,8 +75,8 @@ export const initializeLanguageServiceInstance = (configs: ConfigSet, logger: Lo
   }
   // Initialize memory cache for typescript compiler
   configs.parsedTsConfig.fileNames
-    .filter((fileName) => !configs.isTestFile(fileName))
-    .forEach((fileName) => {
+    .filter((fileName: string) => !configs.isTestFile(fileName))
+    .forEach((fileName: string) => {
       memoryCache.files.set(fileName, {
         version: 0,
       })

src/config/__snapshots__/config-set.spec.ts.snap

@@ -1,5 +1,57 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`_resolveTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and allowSyntheticDefaultImports is false in tsConfig should use correct paths when searching 1`] = `
+Array [
+  Object {
+    "category": 3,
+    "code": 151001,
+    "file": undefined,
+    "length": undefined,
+    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
+    "start": undefined,
+  },
+]
+`;
+
+exports[`_resolveTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and allowSyntheticDefaultImports is false in tsConfig should use given tsconfig path 1`] = `
+Array [
+  Object {
+    "category": 3,
+    "code": 151001,
+    "file": undefined,
+    "length": undefined,
+    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
+    "start": undefined,
+  },
+]
+`;
+
+exports[`_resolveTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and esModuleInterop is not in tsConfig should use correct paths when searching 1`] = `
+Array [
+  Object {
+    "category": 3,
+    "code": 151001,
+    "file": undefined,
+    "length": undefined,
+    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
+    "start": undefined,
+  },
+]
+`;
+
+exports[`_resolveTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and esModuleInterop is not in tsConfig should use given tsconfig path 1`] = `
+Array [
+  Object {
+    "category": 3,
+    "code": 151001,
+    "file": undefined,
+    "length": undefined,
+    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
+    "start": undefined,
+  },
+]
+`;
+
 exports[`customTransformers should return an object containing all resolved transformers 1`] = `
 Object {
   "before": Array [
@@ -55,55 +107,3 @@ exports[`isTestFile should return a boolean value whether the file matches test
 exports[`isTestFile should return a boolean value whether the file matches test pattern 3`] = `true`;
 
 exports[`isTestFile should return a boolean value whether the file matches test pattern 4`] = `true`;
-
-exports[`readTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and allowSyntheticDefaultImports is false in tsConfig should use correct paths when searching 1`] = `
-Array [
-  Object {
-    "category": 3,
-    "code": 151001,
-    "file": undefined,
-    "length": undefined,
-    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
-    "start": undefined,
-  },
-]
-`;
-
-exports[`readTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and allowSyntheticDefaultImports is false in tsConfig should use given tsconfig path 1`] = `
-Array [
-  Object {
-    "category": 3,
-    "code": 151001,
-    "file": undefined,
-    "length": undefined,
-    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
-    "start": undefined,
-  },
-]
-`;
-
-exports[`readTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and esModuleInterop is not in tsConfig should use correct paths when searching 1`] = `
-Array [
-  Object {
-    "category": 3,
-    "code": 151001,
-    "file": undefined,
-    "length": undefined,
-    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
-    "start": undefined,
-  },
-]
-`;
-
-exports[`readTsConfig resolve configFileName normally module in tsConfig is not the same as forced module and esModuleInterop is not in tsConfig should use given tsconfig path 1`] = `
-Array [
-  Object {
-    "category": 3,
-    "code": 151001,
-    "file": undefined,
-    "length": undefined,
-    "messageText": "If you have issues related to imports, you should consider setting \`esModuleInterop\` to \`true\` in your TypeScript configuration file (usually \`tsconfig.json\`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information.",
-    "start": undefined,
-  },
-]
-`;

src/config/config-set.spec.ts

@@ -644,7 +644,7 @@ describe('resolvePath', () => {
   })
 }) // resolvePath
 
-describe('readTsConfig', () => {
+describe('_resolveTsConfig', () => {
   let findConfig!: jest.SpyInstance<string | undefined>
   let readConfig!: jest.SpyInstance<{ config?: any; error?: ts.Diagnostic }>
   let parseConfig!: jest.SpyInstance<ts.ParsedCommandLine>

src/config/config-set.ts

@@ -116,7 +116,7 @@ export class ConfigSet {
   readonly isolatedModules: boolean
   readonly cwd: string
   tsCacheDir: string | undefined
-  parsedTsConfig!: ParsedCommandLine
+  parsedTsConfig!: ParsedCommandLine | Record<string, any>
   customTransformers: CustomTransformers = Object.create(null)
   readonly rootDir: string
   /**
@@ -139,10 +139,7 @@ export class ConfigSet {
    * @internal
    */
   private _stringifyContentRegExp: RegExp | undefined
-  /**
-   * @internal
-   */
-  private _overriddenCompilerOptions: Partial<CompilerOptions> = {
+  protected _overriddenCompilerOptions: Partial<CompilerOptions> = {
     // we handle sourcemaps this way and not another
     sourceMap: true,
     inlineSourceMap: false,
@@ -281,7 +278,10 @@ export class ConfigSet {
     }
     const tsconfigOpt = options.tsConfig ?? options.tsconfig
     const configFilePath = typeof tsconfigOpt === 'string' ? this.resolvePath(tsconfigOpt) : undefined
-    this.parsedTsConfig = this._readTsConfig(typeof tsconfigOpt === 'object' ? tsconfigOpt : undefined, configFilePath)
+    this.parsedTsConfig = this._resolveTsConfig(
+      typeof tsconfigOpt === 'object' ? tsconfigOpt : undefined,
+      configFilePath,
+    )
     // throw errors if any matching wanted diagnostics
     this.raiseDiagnostics(this.parsedTsConfig.errors, configFilePath)
 
@@ -388,10 +388,10 @@ export class ConfigSet {
   /**
    * Load TypeScript configuration. Returns the parsed TypeScript config and
    * any `tsConfig` options specified in ts-jest tsConfig
-   *
-   * @internal
    */
-  private _readTsConfig(compilerOptions?: CompilerOptions, resolvedConfigFile?: string): ParsedCommandLine {
+  protected _resolveTsConfig(compilerOptions?: CompilerOptions, resolvedConfigFile?: string): Record<string, any>
+  // eslint-disable-next-line no-dupe-class-members
+  protected _resolveTsConfig(compilerOptions?: CompilerOptions, resolvedConfigFile?: string): ParsedCommandLine {
     let config = { compilerOptions: Object.create(null) }
     let basePath = normalizeSlashes(this.rootDir)
     const ts = this.compilerModule
@@ -401,6 +401,7 @@ export class ConfigSet {
       : ts.findConfigFile(normalizeSlashes(this.rootDir), ts.sys.fileExists)
     if (configFileName) {
       this.logger.debug({ tsConfigFileName: configFileName }, 'readTsConfig(): reading', configFileName)
+
       const result = ts.readConfigFile(configFileName, ts.sys.readFile)
       // Return diagnostics.
       if (result.error) {
@@ -418,10 +419,8 @@ export class ConfigSet {
 
     // parse json, merge config extending others, ...
     const result = ts.parseJsonConfigFileContent(config, ts.sys, basePath, undefined, configFileName)
-
     const { _overriddenCompilerOptions: forcedOptions } = this
     const finalOptions = result.options
-
     // Target ES5 output by default (instead of ES3).
     if (finalOptions.target === undefined) {
       finalOptions.target = ts.ScriptTarget.ES5
@@ -483,6 +482,7 @@ export class ConfigSet {
         nodeJsVer: process.version,
         compilationTarget: config.compilerOptions.target ?? TARGET_TO_VERSION_MAPPING[compilationTarget],
       })
+
       this.logger.warn(message)
     }
 

src/constants.ts

@@ -1,9 +1,7 @@
-/**
- * @internal
- */
 export const LINE_FEED = '\n'
 export const TS_TSX_REGEX = /\.tsx?$/
 export const JS_JSX_REGEX = /\.jsx?$/
+export const DECLARATION_TYPE_EXT = '.d.ts'
 /**
  * @internal
  * See https://jestjs.io/docs/en/configuration#testmatch-arraystring

src/ts-jest-transformer.ts

@@ -4,7 +4,7 @@ import type { Config } from '@jest/types'
 import type { Logger } from 'bs-logger'
 
 import { ConfigSet } from './config/config-set'
-import { JS_JSX_REGEX, TS_TSX_REGEX } from './constants'
+import { DECLARATION_TYPE_EXT, JS_JSX_REGEX, TS_TSX_REGEX } from './constants'
 import { stringify } from './utils/json'
 import { JsonableValue } from './utils/jsonable-value'
 import { rootLogger } from './utils/logger'
@@ -24,14 +24,8 @@ export class TsJestTransformer implements Transformer {
    */
   private static readonly _cachedConfigSets: CachedConfigSet[] = []
   protected readonly logger: Logger
-  /**
-   * @internal
-   */
-  private _transformCfgStr!: string
-  /**
-   * @internal
-   */
-  private _tsJestCfgSet!: ConfigSet
+  protected _transformCfgStr!: string
+  protected _configSet!: ConfigSet
 
   constructor() {
     this.logger = rootLogger.child({ namespace: 'ts-jest-transformer' })
@@ -49,10 +43,10 @@ export class TsJestTransformer implements Transformer {
 
     let result: string | TransformedSource
     const source: string = input
-    const { hooks } = this._tsJestCfgSet
-    const shouldStringifyContent = this._tsJestCfgSet.shouldStringifyContent(filePath)
-    const babelJest = shouldStringifyContent ? undefined : this._tsJestCfgSet.babelJestTransformer
-    const isDefinitionFile = filePath.endsWith('.d.ts')
+    const { hooks } = this._configSet
+    const shouldStringifyContent = this._configSet.shouldStringifyContent(filePath)
+    const babelJest = shouldStringifyContent ? undefined : this._configSet.babelJestTransformer
+    const isDefinitionFile = filePath.endsWith(DECLARATION_TYPE_EXT)
     const isJsFile = JS_JSX_REGEX.test(filePath)
     const isTsFile = !isDefinitionFile && TS_TSX_REGEX.test(filePath)
     if (shouldStringifyContent) {
@@ -61,15 +55,15 @@ export class TsJestTransformer implements Transformer {
     } else if (isDefinitionFile) {
       // do not try to compile declaration files
       result = ''
-    } else if (!this._tsJestCfgSet.parsedTsConfig.options.allowJs && isJsFile) {
+    } else if (!this._configSet.parsedTsConfig.options.allowJs && isJsFile) {
       // we've got a '.js' but the compiler option `allowJs` is not set or set to false
       this.logger.warn({ fileName: filePath }, interpolate(Errors.GotJsFileButAllowJsFalse, { path: filePath }))
 
       result = source
     } else if (isJsFile || isTsFile) {
       // transpile TS code (source maps are included)
       /* istanbul ignore if */
-      result = this._tsJestCfgSet.tsCompiler.compile(source, filePath)
+      result = this._configSet.tsCompiler.compile(source, filePath)
     } else {
       // we should not get called for files with other extension than js[x], ts[x] and d.ts,
       // TypeScript will bail if we try to compile, and if it was to call babel, users can
@@ -131,7 +125,7 @@ export class TsJestTransformer implements Transformer {
     )
     if (ccs) {
       this._transformCfgStr = ccs.transformerCfgStr
-      this._tsJestCfgSet = ccs.configSet
+      this._configSet = ccs.configSet
     } else {
       // try to look-it up by stringified version
       const serializedJestCfg = stringify(jestConfig)
@@ -144,24 +138,24 @@ export class TsJestTransformer implements Transformer {
         // the config, and then it calls the transformer with the proper object
         serializedCcs.jestConfig.value = jestConfig
         this._transformCfgStr = serializedCcs.transformerCfgStr
-        this._tsJestCfgSet = serializedCcs.configSet
+        this._configSet = serializedCcs.configSet
       } else {
         // create the new record in the index
         this.logger.info('no matching config-set found, creating a new one')
 
-        this._tsJestCfgSet = new ConfigSet(jestConfig)
+        this._configSet = new ConfigSet(jestConfig)
         this._transformCfgStr = new JsonableValue({
-          digest: this._tsJestCfgSet.tsJestDigest,
-          babel: this._tsJestCfgSet.babelConfig,
+          digest: this._configSet.tsJestDigest,
+          babel: this._configSet.babelConfig,
           ...jestConfig,
           tsconfig: {
-            options: this._tsJestCfgSet.parsedTsConfig.options,
-            raw: this._tsJestCfgSet.parsedTsConfig.raw,
+            options: this._configSet.parsedTsConfig.options,
+            raw: this._configSet.parsedTsConfig.raw,
           },
         }).serialized
         TsJestTransformer._cachedConfigSets.push({
           jestConfig: new JsonableValue(jestConfig),
-          configSet: this._tsJestCfgSet,
+          configSet: this._configSet,
           transformerCfgStr: this._transformCfgStr,
         })
       }