It is very easy to write incomplete assertions when using some test frameworks. This rule enforces complete assertions in the following cases:
- Fest:
assertThat is not followed by an assertion invocation
- AssertJ:
assertThat is not followed by an assertion invocation
- Mockito:
verify is not followed by a method invocation
- Truth:
assertXXX is not followed by an assertion invocation
In such cases, what is intended to be a test doesn’t actually verify anything
Noncompliant code example
// Fest
boolean result = performAction();
// let's now check that result value is true
assertThat(result); // Noncompliant; nothing is actually checked, the test passes whether "result" is true or false
// Mockito
List mockedList = Mockito.mock(List.class);
mockedList.add("one");
mockedList.clear();
// let's check that "add" and "clear" methods are actually called
Mockito.verify(mockedList); // Noncompliant; nothing is checked here, oups no call is chained to verify()
Compliant solution
// Fest
boolean result = performAction();
// let's now check that result value is true
assertThat(result).isTrue();
// Mockito
List mockedList = Mockito.mock(List.class);
mockedList.add("one");
mockedList.clear();
// let's check that "add" and "clear" methods are actually called
Mockito.verify(mockedList).add("one");
Mockito.verify(mockedList).clear();
Exceptions
Variable assignments and return statements are skipped to allow helper methods.
private BooleanAssert check(String filename, String key) {
String fileContent = readFileContent(filename);
performReplacements(fileContent);
return assertThat(fileContent.contains(key)); // No issue is raised here
}
@Test
public void test() {
check("foo.txt", "key1").isTrue();
check("bar.txt", "key2").isTrue();
}
