Error reporting (#59)

* Ensure provided externs are leveraged
* Ensure transformer externs are not overwritten by provided externs
* Remove pasted type
* Error Reporting tests
* Logging indicates closure-compiler-npm might be swallowing the data
* Tests for warnings regarding mixing warning_level and language_out

Author: kristoferbaxter

package-lock.json

@@ -55,7 +55,13 @@ export default function(
     }
 
     instance.run(async (exitCode: number, code: string, stdErr: string) => {
-      if (exitCode !== 0) {
+      if (
+        'warning_level' in compileOptions &&
+        compileOptions.warning_level === 'VERBOSE' &&
+        stdErr !== ''
+      ) {
+        reject(new Error(`Google Closure Compiler ${stdErr}`));
+      } else if (exitCode !== 0) {
         reject(new Error(`Google Closure Compiler exit ${exitCode}: ${stdErr}`));
       } else {
         resolve(await postCompilation(code, chunk, transforms));

src/compiler.ts

@@ -19,6 +19,11 @@ import { ModuleFormat, OutputOptions } from 'rollup';
 import { CompileOptions } from 'google-closure-compiler';
 import { sync } from 'temp-write';
 
+export const ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_UNSPECIFIED =
+  'Providing the warning_level=VERBOSE compile option also requires a valid language_out compile option.';
+export const ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_INVALID =
+  'Providing the warning_level=VERBOSE and language_out=NO_TRANSPILE compile option will remove warnings.';
+
 /**
  * Checks if output format is ESM
  * @param format
@@ -29,6 +34,20 @@ export const isESMFormat = (format?: ModuleFormat | 'esm'): boolean => {
   return format === 'esm' || format === 'es';
 };
 
+/**
+ * Throw Errors if compile options will result in unexpected behaviour.
+ * @param compileOptions
+ */
+const validateCompileOptions = (compileOptions: CompileOptions): void => {
+  if ('warning_level' in compileOptions && compileOptions.warning_level === 'VERBOSE') {
+    if (!('language_out' in compileOptions)) {
+      throw new Error(ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_UNSPECIFIED);
+    } else if ('language_out' in compileOptions && compileOptions.language_out === 'NO_TRANSPILE') {
+      throw new Error(ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_INVALID);
+    }
+  }
+};
+
 /**
  * Generate default Closure Compiler CompileOptions an author can override if they wish.
  * These must be derived from configuration or input sources.
@@ -88,6 +107,7 @@ export default function(
   const mapFile = sync('');
   let externs: Array<string> = [];
 
+  validateCompileOptions(compileOptions);
   if ('externs' in compileOptions) {
     switch (typeof compileOptions.externs) {
       case 'boolean':

src/options.ts

@@ -0,0 +1,47 @@
+/**
+ * Copyright 2018 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import test from 'ava';
+import compile, {ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_UNSPECIFIED, ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_INVALID} from '../../transpile/options';
+
+test('with no language out set, and warnings set to verbose... an error is returned', t => {
+  try {
+    compile({
+      warning_level: 'VERBOSE',
+    }, {
+      format: 'es',
+    }, 'var x = 1;', []);
+
+    t.fail('compile completed without throwing an error.');
+  } catch (e) {
+    t.is(e.message, ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_UNSPECIFIED);
+  }
+});
+
+test('with language out set to no_transpile, and warnings set to verbose... an error is returned', t => {
+  try {
+    compile({
+      warning_level: 'VERBOSE',
+      language_out: 'NO_TRANSPILE',
+    }, {
+      format: 'es',
+    }, 'var x = 1;', []);
+
+    t.fail('compile completed without throwing an error.');
+  } catch (e) {
+    t.is(e.message, ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_INVALID);
+  }
+});

test/closure-config/warning-level.js

@@ -0,0 +1 @@
+console.log(document.getElementById(1));

test/error-reporting/fixtures/warnings.esm.advanced.js

@@ -0,0 +1 @@
+console.log(document.getElementById(1));

test/error-reporting/fixtures/warnings.esm.default.js

@@ -0,0 +1 @@
+console.log(document.getElementById(1));

test/error-reporting/fixtures/warnings.js

@@ -0,0 +1,63 @@
+/**
+ * Copyright 2018 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import test from 'ava';
+import compiler from '../../transpile';
+import * as rollup from 'rollup';
+import * as fs from 'fs';
+import { join } from 'path';
+import { promisify } from 'util';
+
+const readFile = promisify(fs.readFile);
+const closureFlags = {
+  default: {
+    warning_level: 'VERBOSE',
+    language_out: 'ECMASCRIPT5_STRICT',
+  },
+  advanced: {
+    warning_level: 'VERBOSE',
+    compilation_level: 'ADVANCED_OPTIMIZATIONS',
+    language_out: 'ECMASCRIPT5_STRICT',
+  },
+};
+
+async function compile(name, option) {
+  const bundle = await rollup.rollup({
+    input: `test/${name}/fixtures/warnings.js`,
+    plugins: [
+      compiler(closureFlags[option]),
+    ],
+  });
+
+  return {
+    minified: await readFile(join(`test/${name}/fixtures/warnings.esm.${option}.js`), 'utf8'),
+    code: (await bundle.generate({
+      format: 'es',
+      sourcemap: true,
+    })).code,
+  };
+}
+
+Object.keys(closureFlags).forEach(option => {
+  test(`provides warnings – es, ${option}`, async t => {
+    try {
+      await compile('error-reporting', option);
+      t.fail('successfully built files without warning about input');
+    } catch(e) {
+      t.pass();
+    }
+  });
+});