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// Copyright (C) 2019 The Android Open Source Project
//
// 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.
package com.google.gerrit.testing;
/** Static JUnit utility methods. */
public class GerritJUnit {
/**
* Assert that an exception is thrown by a block of code.
*
* <p>This method is source-compatible with <a
* href="https://junit.org/junit4/javadoc/latest/org/junit/Assert.html#assertThrows(java.lang.Class,%20org.junit.function.ThrowingRunnable)">JUnit
* 4.13 beta</a>.
*
* <p>This construction is recommended by the Truth team for use in conjunction with asserting
* over a {@code ThrowableSubject} on the return type:
*
* <pre>
* MyException e = assertThrows(MyException.class, () -> doSomething(foo));
* assertThat(e).isInstanceOf(MySubException.class);
* assertThat(e).hasMessageThat().contains("sub-exception occurred");
* </pre>
*
* @param throwableClass expected exception type.
* @param runnable runnable containing arbitrary code.
* @return exception that was thrown.
*/
public static <T extends Throwable> T assertThrows(
Class<T> throwableClass, ThrowingRunnable runnable) {
try {
runnable.run();
} catch (Throwable t) {
if (!throwableClass.isInstance(t)) {
throw new AssertionError(
"expected "
+ throwableClass.getName()
+ " but "
+ t.getClass().getName()
+ " was thrown",
t);
}
@SuppressWarnings("unchecked")
T toReturn = (T) t;
return toReturn;
}
throw new AssertionError(
"expected " + throwableClass.getName() + " but no exception was thrown");
}
@FunctionalInterface
public interface ThrowingRunnable {
void run() throws Throwable;
}
private GerritJUnit() {}
}