toString() seems to be broken on 3.6.28

[ultrasecreth]

Hi guys, I think the toString() method was broken recently, I have a test for mockito-scala that checks a mock toString invocation returns its name, but if I try to update to said version it returns the standard Object implementation of toString.

I tried with the "pure" Java API of Mockito and the same thing happens

Thanks!

[TimvdLippe]

The release diff (v3.6.0...v3.6.28) points to #2098 most likely. Can you do a bisect to figure out if that is indeed the problematic PR?

[rkeen-siemens]

Possibly related and maybe helpful in diagnosing is that attempting to work around this issue by adding an explicit stub for toString (e.g. when(someMock.toString()).thenReturn("someMock")) will cause a MissingMethodInvocationException:

org.mockito.exceptions.misusing.MissingMethodInvocationException: 
when() requires an argument which has to be 'a method call on a mock'.
For example:
    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
   Mocking methods declared on non-public parent classes is not supported.
2. inside when() you don't call method on mock but on some other object.

[TimvdLippe]

Could you try downgrading ByteBuddy to 1.10.15 and see if that resolves the issue?

[pitschr]

I can confirm. I am facing the same issue when upgrading from 3.2.0 to 3.7.7.

[JanMosigItemis]

Hi there,

I came across this bug and decided to have a look. I cannot reproduce it. Maybe I've got something wrong here. Anyway, I provided a test repository with a test build which we may use to get behind things here.

https://github.com/JanMosigItemis/mockito_issue_2154

Let me know how things go 👋

[pitschr]

Hi @JanMosigItemis

I was able to reproduce the issue with your test repository. Just replace "mockito-core" with "mockito-inline"

            <dependency>
                <groupId>org.mockito</groupId>
                <artifactId>mockito-core</artifactId>
                <version>${mockito.version}</version>
                <scope>test</scope>
            </dependency>

            <dependency>
                <groupId>org.mockito</groupId>
                <artifactId>mockito-inline</artifactId>
                <version>${mockito.version}</version>
                <scope>test</scope>
            </dependency>

You should get:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running de.itemis.jmo.mockito.issue2154.MockitoIssue2154JUnit5Test
[ERROR] Tests run: 2, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 1.526 s <<< FAILURE! - in de.itemis.jmo.mockito.issue2154.MockitoIssue2154JUnit5Test
[ERROR] test_stubbed_to_string_works  Time elapsed: 0.054 s  <<< ERROR!
org.mockito.exceptions.misusing.MissingMethodInvocationException: 

when() requires an argument which has to be 'a method call on a mock'.
For example:
    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
   Mocking methods declared on non-public parent classes is not supported.
2. inside when() you don't call method on mock but on some other object.

	at de.itemis.jmo.mockito.issue2154.MockitoIssue2154JUnit5Test.test_stubbed_to_string_works(MockitoIssue2154JUnit5Test.java:26)

[INFO] Running de.itemis.jmo.mockito.issue2154.MockitoIssue2154JUnit4Test
[ERROR] Tests run: 2, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.041 s <<< FAILURE! - in de.itemis.jmo.mockito.issue2154.MockitoIssue2154JUnit4Test
[ERROR] test_stubbed_to_string_works  Time elapsed: 0.018 s  <<< ERROR!
org.mockito.exceptions.misusing.MissingMethodInvocationException: 

when() requires an argument which has to be 'a method call on a mock'.
For example:
    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
   Mocking methods declared on non-public parent classes is not supported.
2. inside when() you don't call method on mock but on some other object.

	at de.itemis.jmo.mockito.issue2154.MockitoIssue2154JUnit4Test.test_stubbed_to_string_works(MockitoIssue2154JUnit4Test.java:26)

[INFO] 
[INFO] Results:
[INFO] 
[ERROR] Errors: 
[ERROR]   MockitoIssue2154JUnit4Test.test_stubbed_to_string_works:26 MissingMethodInvocation
[ERROR]   MockitoIssue2154JUnit5Test.test_stubbed_to_string_works:26 MissingMethodInvocation
[INFO] 
[ERROR] Tests run: 4, Failures: 0, Errors: 2, Skipped: 0

Let me know if this info is enough for you or if I should fork your repo.

[JanMosigItemis]

Thx @pitschr I can reproduce now. The problem is also present in the latest mockito-inline release 3.7.7.

[JanMosigItemis]

@TimvdLippe I downgraded to byte buddy 1.10.15 via maven exclusion and got the same result.

[JanMosigItemis]

I had a hunch that in https://github.com/mockito/mockito/pull/2098/files#diff-749d9baac17dc6e18e7db9ee686a840d65ac746dc291b591b37834ba4c8261d1R273 the line targets.remove(Object.class); could be the culprit. I removed it on my local machine, build mockito-inline 3.7.9 and used it in my test repo. Works like a charm. Now I've got too few internal mockito knowledge in order to come up with a decent PR on this, bc I don't know exactly why this line has been introduced and if it would be safe to simply remove it. Any thoughts on this?

[TimvdLippe]

Thanks for the investigation @JanMosigItemis ! In general, if our full test suite passes with that line removed, it should be safe to do so. Please add a regression test to our test suite as well and then feel free to open a PR for it!

[JanMosigItemis]

Ok, I'll try.