About Truth

Truth is a Java test assertion framework that provides assertions/propositions to apply to objects-under-test. It is intended to be used with the JUnit test infrastructure, and can be used in the context of unit or integration tests.

Truth seeks to apply a fluent interface to testing, and was inspired by FEST, and is the main way that Google writes its android and java tests internally. Its goal is to allow for tests whose assertions are readable and match a quasi-english style, such as assertThat(someString).contains("some substring"). More readable tests make for less error-prone tests.

Truth is an open-source project hosted at Github and is permissively licensed under Apache 2.0, and its main website can be found here.

v 0.29 - pushing towards 1.0

Newly Supported Types

• AtomicLongMap

Changes to existing Subjects and Core classes

• Preliminary versions of "Fuzzy Equality" for doubles/floats. See DoublesSubject for
  new APIs, and we'll be updating the docs on fuzzy equality soon.
• Prefer isEqualTo instead of equals since that is a method with a fairly precise
  meaning in Java, and we were hijacking it. .equals() shouldn't be called on Subject
  implementations.
• Multidimensional Array support in ObjectArraySubject
• Lots of renames and deprecations.
• SPI/API cleanup
  • marking a lot of subjects or their methods final, or noting where we can't
  • start making parts of the infrastructure more in line with the Open/Closed Principle
    (final methods, etc.)
  • stop storing "failure message" in the TestVerb, part 1

New Extensions

• An extension/contrib submodule, for things we want to ship with Truth,
  but which may need to be separate artifacts, mostly due to dependency
  issues or general bloat. Including our first entry: RE2J

  Support for MessageLite protocol buffers is also in extensions, but not released
  in 0.29.

Fixes

• Some cleanups of generics
• Message improvements:
  • Trim some stack trace of the obvious truth frames, to make it clearer where the
    locus of error is. (i.e. who needs to see Subject.failComparing() in the stack trace?)
  • ThrowableSubject uses string comparision where reasonable (to take advantage of
    JUnit's ComparisonFailure)
  • fix BooleanSubject's handling of null in failure messaging
  • other message improvements

Miscellaneous

• Apply @CheckReturnValue across a wide range of methods (on by default).
  • Users are strongly advised to use error-prone in their builds, to ensure
    that this is checked, and the compiler errors out when people fail to call the
    following chained methods.
• build and continuous test system fixes
• more recent upstream dependencies
• full formating of the codebase using google-java-format
• various improvements from error-prone
• improvements to the examples
• more flesh out some holes in the tests

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Note: various methods are being deprecated in preparation for 1.0. A penultimate
pre-1.0 release will be cut with those deprecated methods intact. Then a 1.0 will
be released with those methods removed. This should give people a chance to
get the 1.0 features and benefits, but have a nice transition phase.