Package com.google.common.truth

Class Subject

    • Constructor Detail

      • Subject

        protected Subject​(FailureMetadata metadata,
                  @Nullable Object actual)
        The constructor is for use by subclasses only. If you want to create an instance of this class itself, call check(...).that(actual).

    • Method Detail

      • isNull

        public void isNull()
        Checks that the value under test is null.

      • isNotNull

        public void isNotNull()
        Checks that the value under test is not null.

        Kotlin users: A call to assertThat(foo).isNotNull() does not perform a smart cast on foo. If you require a smart cast, consider using foo!! or assertNotNull(foo) instead. The tradeoffs are that those will look different than any surrounding Truth assertions and that they will produce somewhat worse failure messages.

      • isEqualTo

        public void isEqualTo​(@Nullable Object expected)
        Checks that the value under test is equal to the given object. For the purposes of this comparison, two objects are equal if any of the following is true:

        Note: This method does not test the Object.equals(java.lang.Object) implementation itself; it assumes that method is functioning correctly according to its contract. Testing an equals implementation requires a utility such as guava-testlib's EqualsTester.

        In some cases, this method might not even call equals. It may instead perform other tests that will return the same result as long as equals is implemented according to the contract for its type.

      • isNotEqualTo

        public void isNotEqualTo​(@Nullable Object other)
        Checks that the value under test is not equal to the given object. The meaning of equality is the same as for the isEqualTo(java.lang.Object) method.

      • isSameInstanceAs

        public final void isSameInstanceAs​(@Nullable Object expected)
        Checks that the value under test is the same instance as the given object.

        This method considers null to be "the same instance as" null and not the same instance as anything else.

      • isNotSameInstanceAs

        public final void isNotSameInstanceAs​(@Nullable Object other)
        Checks that the value under test is not the same instance as the given object.

        This method considers null to be "the same instance as" null and not the same instance as anything else.

      • isInstanceOf

        public void isInstanceOf​(@Nullable Class<?> clazz)
        Checks that the value under test is an instance of the given class.

        Kotlin users: A call to assertThat(foo).isInstanceOf(Bar::class.java) does not perform a smart cast on foo. If you require a smart cast, consider using foo as Bar or assertIs<Bar>(foo) instead. The tradeoffs are that those will look different than any surrounding Truth assertions and that they will produce worse failure messages (for example, by not including the actual value, only its type).

      • isNotInstanceOf

        public void isNotInstanceOf​(@Nullable Class<?> clazz)
        Checks that the value under test is not an instance of the given class.

      • isIn

        public void isIn​(@Nullable Iterable<?> iterable)
        Checks that the value under test is equal to any element in the given iterable.

      • isNotIn

        public void isNotIn​(@Nullable Iterable<?> iterable)
        Checks that the value under test is not equal to any element in the given iterable.

      • actualCustomStringRepresentation

        @ForOverride
protected String actualCustomStringRepresentation()
        Returns a string representation of the actual value for inclusion in failure messages.

        Subjects should override this with care.

        By default, this method returns String.valueOf(getActualValue()) for most types. It does have some special logic for a few cases, like arrays.

      • check

        protected final StandardSubjectBuilder check​(String format,
                                             @Nullable Object... args)
        Returns a builder for creating a derived subject.

        Derived subjects retain the FailureStrategy and messages of the current subject, and in some cases, they automatically supplement their failure message with information about the original subject.

        For example, ThrowableSubject.hasMessageThat(), which returns a StringSubject, is implemented with check("getMessage()").that(actual.getMessage()).

        The arguments to check describe how the new subject was derived from the old, formatted like a chained method call. This allows Truth to include that information in its failure messages. For example, assertThat(caught).hasCauseThat().hasMessageThat() will produce a failure message that includes the string "throwable.getCause().getMessage()," thanks to internal check calls that supplied "getCause()" and "getMessage()" as arguments.

        If the method you're delegating to accepts parameters, you can pass check a format string. For example, MultimapSubject.valuesForKey(java.lang.Object) calls check("valuesForKey(%s)", key).

        If you aren't really delegating to an instance method on the actual value -- maybe you're calling a static method, or you're calling a chain of several methods -- you can supply whatever string will be most useful to users. For example, if you're delegating to getOnlyElement(actual.colors()), you might call check("onlyColor()").

        Parameters:
        format - a template with %s placeholders
        args - the arguments to be inserted into those placeholders

      • ignoreCheck

        protected final StandardSubjectBuilder ignoreCheck()
        Begins a new call chain that ignores any failures. This is useful for subjects that normally delegate with to other subjects by using check(java.lang.String, java.lang.Object...) but have already reported a failure. In such cases it may still be necessary to return a Subject instance even though any subsequent assertions are meaningless. For example, if a user chains together more ThrowableSubject.hasCauseThat() calls than the actual exception has causes, hasCauseThat returns ignoreCheck().that(... a dummy exception ...).

      • failWithActual

        protected final void failWithActual​(String key,
                                    @Nullable Object value)
        Fails, reporting a message with two "facts":
        • key: value
        • but was: actual value.

        This is the simplest failure API. For more advanced needs, see the other overload and failWithoutActual.

        Example usage: The check contains(String) calls failWithActual("expected to contain", string).

        Note: While Truth's fail*() methods usually throw AssertionError, they do not do so in all cases: When users use an alternative FailureStrategy, such as Expect, the fail*() methods may instead record the failure somewhere and then return. To accommodate this, Subject methods should typically return after calling a fail*() method, rather than continue onward to potentially fail a second time or throw an exception. For cases in which a method needs to return another Subject to the user, see ignoreCheck().

      • failWithActual

        protected final void failWithActual​(Fact first,
                                    Fact... rest)
        Fails, reporting a message with the given facts, followed by an automatically added fact of the form:
        • but was: actual value.

        If you have only one fact to report (and it's a key-value fact), prefer the simpler overload.

        Example usage: The check isEmpty() calls failWithActual(simpleFact("expected to be empty")).

        Note: While Truth's fail*() methods usually throw AssertionError, they do not do so in all cases: When users use an alternative FailureStrategy, such as Expect, the fail*() methods may instead record the failure somewhere and then return. To accommodate this, Subject methods should typically return after calling a fail*() method, rather than continue onward to potentially fail a second time or throw an exception. For cases in which a method needs to return another Subject to the user, see ignoreCheck().

      • failWithoutActual

        protected final void failWithoutActual​(Fact first,
                                       Fact... rest)
        Fails, reporting a message with the given facts, without automatically adding the actual value.

        Most failure messages should report the actual value, so most checks should call failWithActual instead. However, failWithoutActual is useful in some cases:

        • when the actual value is obvious from the rest of the message. For example, isNotEmpty() calls failWithoutActual(simpleFact("expected not to be empty").
        • when the actual value shouldn't come last or should have a different key than the default of "but was." For example, isNotWithin(...).of(...) calls failWithoutActual so that it can put the expected and actual values together, followed by the tolerance.

        Example usage: The check isEmpty() calls failWithActual(simpleFact("expected to be empty")).

        Note: While Truth's fail*() methods usually throw AssertionError, they do not do so in all cases: When users use an alternative FailureStrategy, such as Expect, the fail*() methods may instead record the failure somewhere and then return. To accommodate this, Subject methods should typically return after calling a fail*() method, rather than continue onward to potentially fail a second time or throw an exception. For cases in which a method needs to return another Subject to the user, see ignoreCheck().