Class Expect
java.lang.Object
com.google.common.truth.StandardSubjectBuilder
com.google.common.truth.Expect
- All Implemented Interfaces:
TestRule
@GwtIncompatible("JUnit4")
public final class Expect
extends StandardSubjectBuilder
implements TestRule
A
TestRule
that batches up all failures encountered during a test, and reports them all
together at the end (similar to ErrorCollector
). It is also useful for making assertions
from other threads or from within callbacks whose exceptions would be swallowed or logged, rather
than propagated out to fail the test. (AssertJ has a similar feature called "soft assertions"; however, soft
assertions are not safe for concurrent use.)
Usage:
If both of the assertions above fail, the test will fail with an exception that contains information about both.@Rule public final Expect expect = Expect.create();
...
expect.that(results).containsExactly(...);
expect.that(errors).isEmpty();
Expect
may be used concurrently from multiple threads. However, multithreaded tests
still require care:
Expect
has no way of knowing when all your other test threads are done. It simply checks for failures when the main thread finishes executing the test method. Thus, you must ensure that any background threads complete their assertions before then, or your test may ignore their results.- Assertion failures are not the only exceptions that may occur in other threads. For maximum
safety, multithreaded tests should check for such exceptions regardless of whether they use
Expect
. (Typically, this means callingget()
on anyFuture
returned by a method likeexecutor.submit(...)
. It might also include checking for unexpected log messages or reading metrics that count failures.) If your tests already check for exceptions from a thread, then that will cover any exception from plainassertThat
.
To record failures for the purpose of testing that an assertion fails when it should, see
ExpectFailure
.
For more on this class, see the documentation page.
-
Method Summary
Modifier and TypeMethodDescriptionapply
(Statement base, Description description) static Expect
create()
Creates a new instance.boolean
Methods inherited from class com.google.common.truth.StandardSubjectBuilder
about, about, fail, forCustomFailureStrategy, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, that, withMessage, withMessage