Support es modules (#1583)

Ref #1579

In config of course. Projects with type:module can now use modules to
export config

```js
export default {
  plugins: []
}
```

Also added support for resolving svgo.config.mjs and svgo.config.cjs.

Moved loadConfig tests to svgo-node tests.

mjs test is skipped for now in node 10, just don't use modules there

lib/svgo-node.js

@@ -2,6 +2,7 @@
 
 const os = require('os');
 const fs = require('fs');
+const { pathToFileURL } = require('url');
 const path = require('path');
 const {
   extendDefaultPlugins,
@@ -13,7 +14,25 @@ exports.extendDefaultPlugins = extendDefaultPlugins;
 exports.createContentItem = createContentItem;
 
 const importConfig = async (configFile) => {
-  const config = require(configFile);
+  let config;
+  try {
+    // dynamic import expects file url instead of path and may fail
+    // when windows path is provided
+    const { default: imported } = await import(pathToFileURL(configFile));
+    config = imported;
+  } catch (importError) {
+    // TODO remove require in v3
+    try {
+      config = require(configFile);
+    } catch (requireError) {
+      // throw original error if es module is detected
+      if (requireError.code === 'ERR_REQUIRE_ESM') {
+        throw importError;
+      } else {
+        throw requireError;
+      }
+    }
+  }
   if (config == null || typeof config !== 'object' || Array.isArray(config)) {
     throw Error(`Invalid config file "${configFile}"`);
   }
@@ -40,9 +59,17 @@ const loadConfig = async (configFile, cwd = process.cwd()) => {
   let dir = cwd;
   // eslint-disable-next-line no-constant-condition
   while (true) {
-    const file = path.join(dir, 'svgo.config.js');
-    if (await isFile(file)) {
-      return await importConfig(file);
+    const js = path.join(dir, 'svgo.config.js');
+    if (await isFile(js)) {
+      return await importConfig(js);
+    }
+    const mjs = path.join(dir, 'svgo.config.mjs');
+    if (await isFile(mjs)) {
+      return await importConfig(mjs);
+    }
+    const cjs = path.join(dir, 'svgo.config.cjs');
+    if (await isFile(cjs)) {
+      return await importConfig(cjs);
     }
     const parent = path.dirname(dir);
     if (dir === parent) {

lib/svgo-node.test.js

@@ -5,7 +5,8 @@
  */
 
 const os = require('os');
-const { optimize } = require('./svgo-node.js');
+const path = require('path');
+const { optimize, loadConfig } = require('./svgo-node.js');
 
 const describeLF = os.EOL === '\r\n' ? describe.skip : describe;
 const describeCRLF = os.EOL === '\r\n' ? describe : describe.skip;
@@ -123,3 +124,94 @@ describeCRLF('with CRLF line-endings', () => {
     );
   });
 });
+
+describe('loadConfig', () => {
+  const cwd = process.cwd();
+  const fixtures = path.join(cwd, './test/fixtures/config-loader');
+
+  test('loads by absolute path', async () => {
+    expect(await loadConfig(path.join(fixtures, 'one/two/config.js'))).toEqual({
+      plugins: [],
+    });
+  });
+
+  test('loads by relative path to cwd', async () => {
+    const config = await loadConfig('one/two/config.js', fixtures);
+    expect(config).toEqual({ plugins: [] });
+  });
+
+  test('searches in cwd and up', async () => {
+    expect(await loadConfig(null, path.join(fixtures, 'one/two'))).toEqual({
+      plugins: [],
+    });
+    expect(
+      await loadConfig(null, path.join(cwd, './test/fixtures/missing'))
+    ).toEqual(null);
+    // TODO remove check in v3
+    if (process.version.startsWith('v10.') === false) {
+      expect(await loadConfig(null, path.join(fixtures, 'mjs'))).toEqual({
+        plugins: ['mjs'],
+      });
+    }
+    expect(await loadConfig(null, path.join(fixtures, 'cjs'))).toEqual({
+      plugins: ['cjs'],
+    });
+  });
+
+  test('fails when specified config does not exist', async () => {
+    try {
+      await loadConfig('{}');
+      expect.fail('Config is loaded successfully');
+    } catch (error) {
+      expect(error.message).toMatch(/Cannot find module/);
+    }
+  });
+
+  test('fails when exported config not an object', async () => {
+    try {
+      await loadConfig(path.join(fixtures, 'invalid-null.js'));
+      expect.fail('Config is loaded successfully');
+    } catch (error) {
+      expect(error.message).toMatch(/Invalid config file/);
+    }
+    try {
+      await loadConfig(path.join(fixtures, 'invalid-array.js'));
+      expect.fail('Config is loaded successfully');
+    } catch (error) {
+      expect(error.message).toMatch(/Invalid config file/);
+    }
+    try {
+      await loadConfig(path.join(fixtures, 'invalid-string.js'));
+      expect.fail('Config is loaded successfully');
+    } catch (error) {
+      expect(error.message).toMatch(/Invalid config file/);
+    }
+  });
+
+  test('handles runtime errors properly', async () => {
+    try {
+      await loadConfig(path.join(fixtures, 'invalid-runtime.js'));
+      expect.fail('Config is loaded successfully');
+    } catch (error) {
+      expect(error.message).toMatch(/plugins is not defined/);
+    }
+    // TODO remove check in v3
+    if (process.version.startsWith('v10.') === false) {
+      try {
+        await loadConfig(path.join(fixtures, 'invalid-runtime.mjs'));
+        expect.fail('Config is loaded successfully');
+      } catch (error) {
+        expect(error.message).toMatch(/plugins is not defined/);
+      }
+    }
+  });
+
+  test('handles MODULE_NOT_FOUND properly', async () => {
+    try {
+      await loadConfig(path.join(fixtures, 'module-not-found.js'));
+      expect.fail('Config is loaded successfully');
+    } catch (error) {
+      expect(error.message).toMatch(/Cannot find module 'unknown-module'/);
+    }
+  });
+});

package.json

@@ -50,7 +50,7 @@
     "!**/*.test.js"
   ],
   "scripts": {
-    "test": "jest --coverage",
+    "test": "NODE_OPTIONS=--experimental-vm-modules jest --maxWorkers=3 --coverage",
     "lint": "eslint --ignore-path .gitignore . && prettier --check \"**/*.js\" --ignore-path .gitignore",
     "fix": "eslint --ignore-path .gitignore --fix . && prettier --write \"**/*.js\" --ignore-path .gitignore",
     "typecheck": "tsc",

test/config/_index.test.js

@@ -1,7 +1,5 @@
 'use strict';
 
-const path = require('path');
-const { loadConfig } = require('../../lib/svgo-node.js');
 const {
   resolvePluginConfig,
   extendDefaultPlugins,
@@ -173,91 +171,6 @@ describe('config', function () {
       );
     });
   });
-
-  describe('config', () => {
-    it('is loaded by absolute path', async () => {
-      const config = await loadConfig(
-        path.join(process.cwd(), './test/config/fixtures/one/two/config.js')
-      );
-      expect(config).toEqual({ plugins: [] });
-    });
-    it('is loaded by relative path to cwd', async () => {
-      const config = await loadConfig(
-        'one/two/config.js',
-        path.join(process.cwd(), './test/config/fixtures')
-      );
-      expect(config).toEqual({ plugins: [] });
-    });
-    it('is searched in cwd and up', async () => {
-      const config = await loadConfig(
-        null,
-        path.join(process.cwd(), './test/config/fixtures/one/two')
-      );
-      expect(config).toEqual({ plugins: [] });
-    });
-    it('gives null when config is not found', async () => {
-      const config = await loadConfig(
-        null,
-        path.join(process.cwd(), './test/config')
-      );
-      expect(config).toEqual(null);
-    });
-    it('is failed when specified config does not exist', async () => {
-      try {
-        await loadConfig('{}');
-        expect.fail('Config is loaded successfully');
-      } catch (error) {
-        expect(error.message).toMatch(/Cannot find module/);
-      }
-    });
-    it('is failed to load when module exports not an object', async () => {
-      try {
-        await loadConfig(
-          path.join(process.cwd(), './test/config/fixtures/invalid-null.js')
-        );
-        expect.fail('Config is loaded successfully');
-      } catch (error) {
-        expect(error.message).toMatch(/Invalid config file/);
-      }
-      try {
-        await loadConfig(
-          path.join(process.cwd(), './test/config/fixtures/invalid-array.js')
-        );
-        expect.fail('Config is loaded successfully');
-      } catch (error) {
-        expect(error.message).toMatch(/Invalid config file/);
-      }
-      try {
-        await loadConfig(
-          path.join(process.cwd(), './test/config/fixtures/invalid-string.js')
-        );
-        expect.fail('Config is loaded successfully');
-      } catch (error) {
-        expect(error.message).toMatch(/Invalid config file/);
-      }
-    });
-    it('handles config errors properly', async () => {
-      try {
-        await loadConfig(
-          null,
-          path.join(process.cwd(), './test/config/fixtures/invalid/config')
-        );
-        expect.fail('Config is loaded successfully');
-      } catch (error) {
-        expect(error.message).toMatch(/plugins is not defined/);
-      }
-    });
-    it('handles MODULE_NOT_FOUND properly', async () => {
-      try {
-        await loadConfig(
-          path.join(process.cwd(), './test/config/fixtures/module-not-found.js')
-        );
-        expect.fail('Config is loaded successfully');
-      } catch (error) {
-        expect(error.message).toMatch(/Cannot find module 'unknown-module'/);
-      }
-    });
-  });
 });
 
 function getPlugin(name, plugins) {

test/fixtures/config-loader/cjs/svgo.config.cjs

@@ -0,0 +1,3 @@
+module.exports = {
+  plugins: ['cjs'],
+};

test/fixtures/config-loader/invalid-runtime.mjs

@@ -0,0 +1 @@
+export default { plugins }; // eslint-disable-line no-undef

test/fixtures/config-loader/mjs/svgo.config.mjs

@@ -0,0 +1,3 @@
+export default {
+  plugins: ['mjs'],
+};