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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

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/*
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Nick Santos
 *   Google Inc.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package com.google.javascript.rhino.testing;

import static com.google.common.truth.Truth.assertThat;
import static com.google.common.truth.Truth.assertWithMessage;
import static com.google.javascript.rhino.testing.TypeSubject.assertType;
import static com.google.javascript.rhino.testing.TypeSubject.types;

import com.google.common.collect.Iterables;
import com.google.javascript.rhino.jstype.JSType;
import java.util.Iterator;
import org.junit.Assert;

/**
 * Helper methods for making assertions about the validity of types.
 * @author [email protected] (Nick Santos)
 */
public class Asserts {
  private Asserts() {} // all static

  public static JSType assertResolvesToSame(JSType type) {
    Assert.assertSame(type, assertValidResolve(type));
    return type;
  }

  /** @return The resolved type */
  public static JSType assertValidResolve(JSType type) {
    TestErrorReporter reporter = new TestErrorReporter();
    JSType resolvedType = type.resolve(reporter);
    assertWithMessage("JSType#resolve should not affect object equality")
        .about(types())
        .that(resolvedType)
        .isEqualTo(type);
    reporter.verifyHasEncounteredAllWarningsAndErrors();
    return resolvedType;
  }

  public static  void
      assertTypeCollectionEquals(Iterable a, Iterable b) {
    assertThat(b).hasSize(Iterables.size(a));
    Iterator aIterator = a.iterator();
    Iterator bIterator = b.iterator();
    while (aIterator.hasNext()) {
      assertType(bIterator.next()).isEqualTo(aIterator.next());
    }
  }

  /**
   * For the given equivalent types, run all type operations that
   * should have trivial solutions (getGreatestSubtype, isEquivalentTo, etc)
   */
  public static void assertEquivalenceOperations(JSType a, JSType b) {
    assertType(a).isEqualTo(a);
    assertType(b).isEqualTo(a);
    assertType(b).isEqualTo(b);

    Assert.assertTrue(a.isSubtypeOf(b));
    Assert.assertTrue(a.isSubtypeOf(a));
    Assert.assertTrue(b.isSubtypeOf(b));
    Assert.assertTrue(b.isSubtypeOf(a));

    assertType(a.getGreatestSubtype(b)).isEqualTo(a);
    assertType(a.getGreatestSubtype(a)).isEqualTo(a);
    assertType(b.getGreatestSubtype(b)).isEqualTo(a);
    assertType(b.getGreatestSubtype(a)).isEqualTo(a);

    assertType(a.getLeastSupertype(b)).isEqualTo(a);
    assertType(a.getLeastSupertype(a)).isEqualTo(a);
    assertType(b.getLeastSupertype(b)).isEqualTo(a);
    assertType(b.getLeastSupertype(a)).isEqualTo(a);

    Assert.assertTrue(a.canCastTo(b));
    Assert.assertTrue(a.canCastTo(a));
    Assert.assertTrue(b.canCastTo(b));
    Assert.assertTrue(b.canCastTo(a));
  }

  /**
   * Assert that the given function throws a particular throwable. This method is inspired by a
   * similar API in JUnit 4.13, but the compiler is currently pinned on 4.12, which doesn't include
   * it.
   */
  @SuppressWarnings("unchecked")
  public static  T assertThrows(
      Class exceptionClass, ThrowingRunnable runnable) {
    try {
      runnable.run();
    } catch (Throwable expectedException) {
      assertThat(expectedException).isInstanceOf(exceptionClass);
      return (T) expectedException; // Unchecked cast. J2CL doesn't support `Class::cast`.
    }

    assertWithMessage("Did not get expected exception: %s", exceptionClass).fail();
    throw new AssertionError("Impossible");
  }

  /** Functional interface for use with {@link #assertThrows}. */
  @FunctionalInterface
  public static interface ThrowingRunnable {
    void run() throws Throwable;
  }
}