feat: strict config file source (#6)

Author: hanseltime

README.md

@@ -43,6 +43,47 @@ You can change your build script in "package.json" as:
 
 Now you can run `npm run build` to build.
 
+### About .swcrc
+
+tswc will always merge your swc configuration file on top of any of the options that were inferred from your tsconfig.
+By default, swc and tswc will look for a .swcrc file and tolerate if there is none found.  However, tswc will respect
+any `--config-file` option that you provide to swc and will even make sure to throw an error if the file is missing.
+
+```shell
+# Example of using a .development.swcrc file to override the base config from tsconfig
+tswc -- --config-file .development.swcrc
+```
+
+As a naive example, if you had a tsconfig.json file that used commonjs compilation, but also wanted to compile an esm version,
+you could set up a .esm.swcrc so that:
+
+```json
+// tsconfig.json
+{
+  "module": "commonjs",
+  "moduleResolution": "node",
+  // Other options
+}
+
+// .esm.swcrc
+{
+  "module": {
+    // This overrides the module "commonjs" of tsconfig to es6
+    "type": "es6"
+  }
+}
+```
+
+The corresponding commands for this project might be something like:
+
+```shell
+# Creates esm syntax compiled files
+tswc -- src -d dist/esm --config-file .esm.swcrc
+
+# Creates commonjs syntax compiled files
+tswc -- src -d dist/esm
+```
+
 ## Notice
 
 Only a subgroup of fields of tsconfig is supported currently. This is done with [tsconfig-to-swcconfig](https://github.com/Songkeys/tsconfig-to-swcconfig). This means that some tsc features may be missing when compiling with this.

src/cli.ts

@@ -8,16 +8,46 @@ import { parse } from 'jsonc-parser'
 
 const cli = cac('tswc')
 
+// These are swc cli arguments that we are also tapping in the wrapper
+const expectedSwcCli = cac('swc')
+expectedSwcCli.option(
+  '--config-file <configFile>',
+  'swc config file - override tsconfig',
+)
+
 cli
   .command('[file]', 'file or directory to build')
-  .allowUnknownOptions()
   .option('--tsconfig <filename>', 'the filename of tsconfig', {
     default: 'tsconfig.json',
   })
   .option('--debug', 'output the final swc config', { default: false })
-  .action((file = '', { tsconfig, debug, configFile = '.swcrc', ...args }) => {
+  .option(
+    '-- <swc cli args>',
+    'the remaining swc arguments like you would normally call',
+  )
+  .action((file = '', options: any) => {
+    const { tsconfig, debug } = options
+    const _swcArgs = options['--']
+    // parse shared swc args here
+    const swcParsedArgs = expectedSwcCli.parse(_swcArgs) as {
+      options: {
+        configFile?: string
+      }
+    }
+    const { configFile } = swcParsedArgs.options
+
+    let oSwcrcPath: string
+    if (configFile) {
+      oSwcrcPath = path.resolve(process.cwd(), configFile)
+      if (!fs.existsSync(oSwcrcPath)) {
+        throw new Error(
+          `Invalid option: --config-file. Could not find file: ${oSwcrcPath}`,
+        )
+      }
+    } else {
+      oSwcrcPath = path.resolve(process.cwd(), '.swcrc')
+    }
     // read .swcrc
-    const oSwcrcPath = path.resolve(process.cwd(), configFile)
     let oSwcOptions = fs.existsSync(oSwcrcPath)
       ? parse(fs.readFileSync(oSwcrcPath, 'utf8'))
       : {}
@@ -36,7 +66,7 @@ cli
 
       // compile
       const swcBin = require.resolve('.bin/swc')
-      const swcArgs = [file, ...args['--'], '--config-file', SWCRC_PATH]
+      const swcArgs = [file, ..._swcArgs, '--config-file', SWCRC_PATH]
       if (debug) {
         console.log(`> swc ${swcArgs.join(' ')}`)
       }

test/cli.test.ts

@@ -9,20 +9,21 @@ const cliBin = path.join(__dirname, '..', 'src', 'cli.ts')
 // const cliBin = path.join(__dirname, '..', 'dist', 'cli.js')
 
 describe('test suite', () => {
-  it('generally work', ({ expect }) => {
+  it('generally works', ({ expect }) => {
     const proc = spawnSync(node, [cliBin], {
       stdio: 'pipe',
     })
     expect(proc.stdout.toString()).toBeTypeOf('string')
     expect(proc.status).toBe(0)
   })
 
-  it('compile some code', ({ expect }) => {
-    // const { stdout } = spawnSync(
+  it('compiles some code', ({ expect }) => {
     const proc = spawnSync(
       node,
       [
         cliBin,
+        '--',
+        // swc args
         path.join(__dirname, 'fixtures', 'src', 'index.ts'),
         '--config-file',
         path.join(__dirname, 'fixtures', 'src', '.swcrc'),
@@ -61,4 +62,25 @@ describe('test suite', () => {
       expect(proc.stderr.toString()).toMatch(/error: unknown option/)
     } catch {}
   })
+  it('throws if the config does not exist', ({ expect }) => {
+    const codePath = path.join(__dirname, 'fixtures', 'src', 'index.ts')
+    try {
+      const proc = spawnSync(
+        node,
+        [
+          cliBin,
+          // swc arguments
+          '--',
+          path.join(__dirname, 'fixtures', 'src', 'index.ts'),
+          '--config-file',
+          path.join(__dirname, 'fixtures', 'src', 'nope.swcrc'),
+        ],
+        { stdio: 'pipe' },
+      )
+      expect(proc.status).toBe(1)
+      expect(proc.stderr.toString()).toMatch(
+        /Invalid option: --config-file. Could not find file:/,
+      )
+    } catch {}
+  })
 })