#1100: adds --show-config to log the resolved configuration

package.json

@@ -123,7 +123,7 @@
     "tslint": "^6.1.0",
     "tslint-config-standard": "^9.0.0",
     "typedoc": "^0.20.20",
-    "typescript": "4.1.2",
+    "typescript": "4.2.2",
     "typescript-json-schema": "^0.42.0",
     "util.promisify": "^1.0.1"
   },

src/bin.ts

@@ -10,7 +10,7 @@ import {
   createRepl,
   ReplService
  } from './repl'
-import { VERSION, TSError, parse, register, createRequire } from './index'
+import { VERSION, TSError, parse, register, createRequire, TSInternal } from './index'
 
 /**
  * Main `bin` functionality.
@@ -30,6 +30,7 @@ export function main (argv: string[] = process.argv.slice(2), entrypointArgs: Re
       '--cwd-mode': Boolean,
       '--script-mode': Boolean,
       '--version': arg.COUNT,
+      '--show-config': Boolean,
 
       // Project options.
       '--cwd': String,
@@ -64,7 +65,8 @@ export function main (argv: string[] = process.argv.slice(2), entrypointArgs: Re
       '-C': '--compiler',
       '-D': '--ignore-diagnostics',
       '-O': '--compiler-options',
-      '--dir': '--cwd'
+      '--dir': '--cwd',
+      '--showConfig': '--show-config'
     }, {
       argv,
       stopAtPositional: true
@@ -80,6 +82,7 @@ export function main (argv: string[] = process.argv.slice(2), entrypointArgs: Re
     '--script-mode': scriptMode,
     '--cwd-mode': cwdMode,
     '--version': version = 0,
+    '--show-config': showConfig,
     '--require': argsRequire = [],
     '--eval': code = undefined,
     '--print': print = false,
@@ -115,6 +118,7 @@ export function main (argv: string[] = process.argv.slice(2), entrypointArgs: Re
     -h, --help                     Print CLI usage
     -v, --version                  Print module version information
     --cwd-mode                     Use current directory instead of <script.ts> for config resolution
+    --show-config                  Print resolved configuration and exit
 
     -T, --transpile-only           Use TypeScript's faster \`transpileModule\`
     -H, --compiler-host            Use TypeScript's compiler host API
@@ -184,6 +188,28 @@ export function main (argv: string[] = process.argv.slice(2), entrypointArgs: Re
     process.exit(0)
   }
 
+  if (showConfig) {
+    const ts = service.ts as any as TSInternal
+    if (typeof ts.convertToTSConfig !== 'function') { // tslint:disable-line:strict-type-predicates
+      console.error('Error: --show-config requires a typescript versions >=3.2 that support --showConfig')
+      process.exit(1)
+    }
+    const json = ts.convertToTSConfig(service.config, service.configFilePath ?? join(cwd, 'ts-node-implicit-tsconfig.json'), service.ts.sys)
+    json['ts-node'] = {
+      ...service.options,
+      experimentalEsmLoader: undefined,
+      compilerOptions: undefined,
+      project: service.configFilePath ?? service.options.project
+    }
+    console.log(
+      // Assumes that all configuration options which can possibly be specified via the CLI are JSON-compatible.
+      // If, in the future, we must log functions, for example readFile and fileExists, then we can implement a JSON
+      // replacer function.
+      JSON.stringify(json, null, 2)
+    )
+    process.exit(0)
+  }
+
   // Create a local module instance based on `cwd`.
   const module = new Module(state.path)
   module.filename = state.path

src/index.spec.ts

@@ -1,7 +1,7 @@
 import { test, TestInterface } from './testlib'
 import { expect } from 'chai'
 import { ChildProcess, exec as childProcessExec, ExecException, ExecOptions } from 'child_process'
-import { join } from 'path'
+import { join, resolve, sep as pathSep } from 'path'
 import semver = require('semver')
 import ts = require('typescript')
 import proxyquire = require('proxyquire')
@@ -35,6 +35,7 @@ function exec (cmd: string, opts: ExecOptions = {}): Promise<TestExecReturn> & {
   )
 }
 
+const ROOT_DIR = resolve(__dirname, '..')
 const TEST_DIR = join(__dirname, '../tests')
 const PROJECT = join(TEST_DIR, 'tsconfig.json')
 const BIN_PATH = join(TEST_DIR, 'node_modules/.bin/ts-node')
@@ -583,6 +584,45 @@ test.suite('ts-node', (test) => {
         )
       })
     })
+
+    if (semver.gte(ts.version, '3.2.0')) {
+      test('--show-config should log resolved configuration', async (t) => {
+        function native (path: string) { return path.replace(/\/|\\/g, pathSep) }
+        function posix (path: string) { return path.replace(/\/|\\/g, '/') }
+        const { err, stdout } = await exec(`${cmd} --showConfig`)
+        expect(err).to.equal(null)
+        t.is(stdout, JSON.stringify({
+          'compilerOptions': {
+            'target': 'es6',
+            'jsx': 'react',
+            'noEmit': false,
+            'strict': true,
+            'typeRoots': [
+              posix(`${ ROOT_DIR }/tests/typings`),
+              posix(`${ ROOT_DIR }/node_modules/@types`)
+            ],
+            'sourceMap': true,
+            'inlineSourceMap': false,
+            'inlineSources': true,
+            'declaration': false,
+            'outDir': './.ts-node',
+            'module': 'commonjs'
+          },
+          'ts-node': {
+            'cwd': native(`${ ROOT_DIR }/tests`),
+            'projectSearchDir': native(`${ ROOT_DIR }/tests`),
+            'project': native(`${ ROOT_DIR }/tests/tsconfig.json`),
+            'require': []
+          }
+        }, null, 2) + '\n')
+      })
+    } else {
+      test('--show-config should log error message when used with old typescript versions', async (t) => {
+        const { err, stderr } = await exec(`${cmd} --showConfig`)
+        expect(err).to.not.equal(null)
+        expect(stderr).to.contain('Error: --show-config requires')
+      })
+    }
   })
 
   test.suite('register', (_test) => {

src/index.ts

@@ -134,14 +134,23 @@ export interface TSCommon {
 
 /**
  * Compiler APIs we use that are marked internal and not included in TypeScript's public API declarations
+ * @internal
  */
-interface TSInternal {
+export interface TSInternal {
   // https://github.com/microsoft/TypeScript/blob/4a34294908bed6701dcba2456ca7ac5eafe0ddff/src/compiler/core.ts#L1906-L1909
   createGetCanonicalFileName (useCaseSensitiveFileNames: boolean): TSInternal.GetCanonicalFileName
+  // https://github.com/microsoft/TypeScript/blob/c117c266e09c80e8a06b24a6e94b9d018f5fae6b/src/compiler/commandLineParser.ts#L2054
+  convertToTSConfig (configParseResult: _ts.ParsedCommandLine, configFileName: string, host: TSInternal.ConvertToTSConfigHost): any
 }
-namespace TSInternal {
+/** @internal */
+export namespace TSInternal {
   // https://github.com/microsoft/TypeScript/blob/4a34294908bed6701dcba2456ca7ac5eafe0ddff/src/compiler/core.ts#L1906
   export type GetCanonicalFileName = (fileName: string) => string
+  // https://github.com/microsoft/TypeScript/blob/c117c266e09c80e8a06b24a6e94b9d018f5fae6b/src/compiler/commandLineParser.ts#L2041
+  export interface ConvertToTSConfigHost {
+    getCurrentDirectory (): string
+    useCaseSensitiveFileNames: boolean
+  }
 }
 
 /**
@@ -430,6 +439,8 @@ export interface Service {
   ignored (fileName: string): boolean
   compile (code: string, fileName: string, lineOffset?: number): string
   getTypeInfo (code: string, fileName: string, position: number): TypeInfo
+  /** @internal */
+  configFilePath: string | undefined
 }
 
 /**
@@ -1051,7 +1062,7 @@ export function create (rawOptions: CreateOptions = {}): Service {
     return true
   }
 
-  return { ts, config, compile, getTypeInfo, ignored, enabled, options }
+  return { ts, config, compile, getTypeInfo, ignored, enabled, options, configFilePath }
 }
 
 /**