Verification of an empty varargs call fails when isNotNull() is used #567
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Thanks for the report |
ChristianSchwarz
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ChristianSchwarz
changed the title
TimvdLippe
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Dec 22, 2022
Using the new `type()`, we can differentiate between matching all varargs or only one argument of the varargs. # Benefits: Because this approach leaves `VarargsMatcher` untouched, it does not require additional existing matchers to implement `VarargsMatcher` to fix issues such as #567. Where as the first PR would require `Null` and `NotNull` to be marked `VarargsMatcher`. This PR creates new variants of `isNotNull` and `isNull` to address #567. Having `InstanceOf` override `type()` provides a workable solution to #1593. Having `equals` override `type` addresses #1222. # Downsides The obvious downside is that this changes the public `ArgumentMatcher` interface, though in a backwards compatible way. ## Known limitation The main limitation I'm aware of, is not a new limitation. It is that it is not possible to assert only a single parameter is passed to the vararg parameter, when using a `VarargMatcher`, e.g. `any()`. (ref: #1593). For example: ```java // Given method: int vararg(String... args); // I want to mock this invocation: mock.vararag("one param"); // ...but not these: mock.vararg(); mock.vararg("more than", "one param"); ``` There is no current way to do this. This is because in the following intuitive mocking: ```java given(mock.vararg(any(String.class))).willReturn(1); ``` ... matches zero or more vararg parameters, as the `any()` method is using `VarargMatcher`. It seems to me that `VarargMatcher` is... a little broken! This is maybe something that should be consider a candiate for fixing in the next major version bump. While it is not possible to fix any `VarargMatcher` based matchers in a backwards compatible way, this the approach in this PR it is possible to mock/verify exactly one vararg param using `isA`, rather than `any`: ```java @test public void shouldMatchExactlyOnParam() { mock.varargs("one param"); verify(mock).varargs(isA(String.class)); } @test public void shouldNotMatchMoreParams() { mock.varargs("two", "params"); verify(mock, never()).varargs(isA(String.class)); } @test public void shouldMatchAnyNumberOfParams() { mock.varargs("two", "params"); verify(mock).varargs(isA(String[].class)); } ``` ... because `isA` does not implement `VarargsMatcher`, and so can work as expected once it implements `type()`. Fixes #2796 Fixes #567 Fixes #584 Fixes #1222 Fixes #1498
TimvdLippe
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Dec 28, 2022
Using the new `type()`, we can differentiate between matching all varargs or only one argument of the varargs. # Benefits: Because this approach leaves `VarargsMatcher` untouched, it does not require additional existing matchers to implement `VarargsMatcher` to fix issues such as #567. Where as the first PR would require `Null` and `NotNull` to be marked `VarargsMatcher`. This PR creates new variants of `isNotNull` and `isNull` to address #567. Having `InstanceOf` override `type()` provides a workable solution to #1593. Having `equals` override `type` addresses #1222. # Downsides The obvious downside is that this changes the public `ArgumentMatcher` interface, though in a backwards compatible way. ## Known limitation The main limitation I'm aware of, is not a new limitation. It is that it is not possible to assert only a single parameter is passed to the vararg parameter, when using a `VarargMatcher`, e.g. `any()`. (ref: #1593). For example: ```java // Given method: int vararg(String... args); // I want to mock this invocation: mock.vararag("one param"); // ...but not these: mock.vararg(); mock.vararg("more than", "one param"); ``` There is no current way to do this. This is because in the following intuitive mocking: ```java given(mock.vararg(any(String.class))).willReturn(1); ``` ... matches zero or more vararg parameters, as the `any()` method is using `VarargMatcher`. It seems to me that `VarargMatcher` is... a little broken! This is maybe something that should be consider a candiate for fixing in the next major version bump. While it is not possible to fix any `VarargMatcher` based matchers in a backwards compatible way, this the approach in this PR it is possible to mock/verify exactly one vararg param using `isA`, rather than `any`: ```java @test public void shouldMatchExactlyOnParam() { mock.varargs("one param"); verify(mock).varargs(isA(String.class)); } @test public void shouldNotMatchMoreParams() { mock.varargs("two", "params"); verify(mock, never()).varargs(isA(String.class)); } @test public void shouldMatchAnyNumberOfParams() { mock.varargs("two", "params"); verify(mock).varargs(isA(String[].class)); } ``` ... because `isA` does not implement `VarargsMatcher`, and so can work as expected once it implements `type()`. Fixes #2796 Fixes #567 Fixes #584 Fixes #1222 Fixes #1498
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With #2807 merged, the second test above can be achieved, not through casts, but through using the variant of @Test
public void shouldMatchVarArgs_isNotNullArray() {
mock.varargs();
verify(mock).varargs((String[])isNotNull(String[].class));
}However, the first test is invalid: @Test
public void shouldMatchVarArgs_isNotNull() {
mock.varargs();
verify(mock).varargs(isNotNull());
}This previously would have matched a |
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The follwing tests fail unexpected with : "Argument(s) are different"
Expected is that the tests pass cause an empty vararg array is not null!
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