assert vs. JUnit Assertions
Today I saw a JUnit test case with a java assertion instead of the JUnit assertions—Are there significant advantages or disadvantages to prefer one over the other?
In JUnit4 the exception (actually Error) thrown by a JUnit assert is the same as the error thrown by the java assert keyword (AssertionError), so it is exactly the same as assertTrue and other than the stack trace you couldn't tell the difference.
That being said, asserts have to run with a special flag in the JVM, causing many tests to appear to pass just because someone forgot to configure the system with that flag when the JUnit tests were run - not good.
In general, because of this, I would argue that using the JUnit assertTrue is the better practice, because it guarantees the test is run, ensures consistency (you sometimes use assertThat or other asserts that are not a java keyword) and if the behavior of JUnit asserts should change in the future (such as hooking into some kind of filter or other future JUnit feature) your code will be able to leverage that.
The real purpose of the assert keyword in java is to be able to turn it off without runtime penalty. That doesn't apply to unit tests.
I prefer JUnit assertions as they offer a richer API than the built-in assert statement and, more importantly do not need to be explicitly enabled unlike assert, which requires the -ea JVM argument.
When a test fails you get more infomation.
assertEquals(1, 2); results in java.lang.AssertionError: expected:<1> but was:<2>
vs
assert(1 == 2); results in java.lang.AssertionError
you can get even more info if you add the message argument to assertEquals
assert 1==2: "1 is not 2";.
assert may be preferable -- for correctness checks which would impact performance and are thus best disabled by default. However my experience is that most assertions should be always-on.
I'd say use JUnit asserts in test cases, and use java's assert in the code. In other words, real code shall never have JUnit dependencies, as obvious, and if it's a test, it should use the JUnit variations of it, never the assert.
I would say if you are using JUnit you should use the JUnit assertions. assertTrue() is basically the same as assert, Otherwise why even use JUnit?
Assert would require more boilerplate. assert without JUnit would require you to write a whole framework.
This may not apply if you exclusively use stuff that's shiny and new, but assert was not introduced into Java until 1.4SE. Therefore, if you must work in an environment with older technology, you may lean towards JUnit for compatibility reasons.
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-eais always enabled inmvn test, no need for-ea. Richer api, good catch. Sometimes I think API is misused in test because it is not part of the application (a in api), I prefer to call it just richer methods.