com.google.common.truth

Class ExpectFailure

java.lang.Object

com.google.common.truth.ExpectFailure

All Implemented Interfaces:

org.junit.rules.TestRule

public final class ExpectFailure
extends Object
implements org.junit.rules.TestRule

A utility for testing that assertions against a custom Subject fail when they should.

Usage:

   AssertionError failure =
       expectFailure(whenTesting -> whenTesting.that(cancelButton).isVisible());
   assertThat(failure).hasMessageThat().contains("visible");

 ...

 private static AssertionError expectFailure(
     ExpectFailure.SimpleSubjectBuilderCallback<UiElementSubject, UiElement> assertionCallback) {
   return ExpectFailure.expectFailureAbout(uiElements(), assertionCallback);
 }
 

Or, if you can't use lambdas:

  @Rule public final ExpectFailure expectFailure = new ExpectFailure();

  ...

     expectFailure.whenTesting().about(uiElements()).that(cancelButton).isVisible();
     assertThat(expectFailure.getFailure()).hasMessageThat().contains("visible");
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ExpectFailure.SimpleSubjectBuilderCallback<S extends Subject<S,A>,A> A "functional interface" for expectFailureAbout() to invoke and capture failures.
static interface	ExpectFailure.StandardSubjectBuilderCallback A "functional interface" for expectFailure() to invoke and capture failures.

Constructor Summary

Constructors

Constructor and Description
ExpectFailure()

Method Summary

Modifier and Type	Method and Description
org.junit.runners.model.Statement	apply(org.junit.runners.model.Statement base, org.junit.runner.Description description)
static AssertionError	expectFailure(ExpectFailure.StandardSubjectBuilderCallback assertionCallback) Static alternative that directly returns the triggered failure.
static <S extends Subject<S,A>,A> AssertionError	expectFailureAbout(Subject.Factory<S,A> factory, ExpectFailure.SimpleSubjectBuilderCallback<S,A> assertionCallback) Static alternative that directly returns the triggered failure.
static <S extends Subject<S,A>,A> AssertionError	expectFailureAbout(SubjectFactory<S,A> factory, ExpectFailure.SimpleSubjectBuilderCallback<S,A> assertionCallback) Deprecated. When you switch from SubjectFactory to Subject.Factory, you'll switch from this overload to the Subject.Factory overload.
AssertionError	getFailure() Returns the captured failure, if one occurred.
StandardSubjectBuilder	whenTesting() Returns a test verb that expects the chained assertion to fail, and makes the failure available via getFailure().

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExpectFailure

public ExpectFailure()

Method Detail

whenTesting

public StandardSubjectBuilder whenTesting()

Returns a test verb that expects the chained assertion to fail, and makes the failure available via getFailure().

An instance of ExpectFailure supports only one whenTesting call per test method. The static expectFailure(com.google.common.truth.ExpectFailure.StandardSubjectBuilderCallback) method, by contrast, does not have this limitation.

getFailure

public AssertionError getFailure()

Returns the captured failure, if one occurred.

expectFailure

public static AssertionError expectFailure(ExpectFailure.StandardSubjectBuilderCallback assertionCallback)

Static alternative that directly returns the triggered failure. This is intended to be used in Java 8 tests similar to expectThrows():

AssertionError failure = expectFailure(whenTesting -> whenTesting.that(4).isNotEqualTo(4));

expectFailureAbout

@Deprecated
public static <S extends Subject<S,A>,A> AssertionError expectFailureAbout(SubjectFactory<S,A> factory,
                                                                                       ExpectFailure.SimpleSubjectBuilderCallback<S,A> assertionCallback)

Deprecated. When you switch from SubjectFactory to Subject.Factory, you'll switch from this overload to the Subject.Factory overload.

Static alternative that directly returns the triggered failure. This is intended to be used in Java 8 tests similar to expectThrows():

AssertionError failure = expectFailureAbout(myTypes(), whenTesting -> whenTesting.that(myType).hasProperty());

expectFailureAbout

public static <S extends Subject<S,A>,A> AssertionError expectFailureAbout(Subject.Factory<S,A> factory,
                                                                           ExpectFailure.SimpleSubjectBuilderCallback<S,A> assertionCallback)

Static alternative that directly returns the triggered failure. This is intended to be used in Java 8 tests similar to expectThrows():

AssertionError failure = expectFailureAbout(myTypes(), whenTesting -> whenTesting.that(myType).hasProperty());

apply

public org.junit.runners.model.Statement apply(org.junit.runners.model.Statement base,
                                               org.junit.runner.Description description)

Specified by:

apply in interface org.junit.rules.TestRule