TBD Logger is mocked

[alisevych]

Description

Logger is in the list of classes to be force mocked.
Why?
Usually user does not want to test logger. So mocking of logger allows to test user code - without danger to face errors with logging.
However this can be turned off with option in "forceStaticMocking" in UtBotJavaApi. And on UI in IDEA:

Expected behavior

(TBD) Probably we need to add comment to the Logger mock like:

// Logger is mocked to exclude it from testing. 
// You can turn this option off here: https://github.com/UnitTestBot/UTBotJava/wiki/Fine-tune-test-generation#classes-to-be-forcedly-mocked
// Then Logger will be analyzed too.

Example

1. Generate tests with default settings for org.utbot.examples.mixed.LoggerExample
2. The following tests are generated:

    public void testExample_LoggerInfo() throws ClassNotFoundException, IllegalAccessException, NoSuchFieldException {
        MockedStatic mockedStatic = null;
        try {
            Class loggerExampleClazz = Class.forName("org.utbot.examples.mixed.LoggerExample");
            Logger prevLogger = ((Logger) getStaticFieldValue(loggerExampleClazz, "logger"));
            try {
                Logger loggerMock = mock(Logger.class);
                ((doNothing()).when(loggerMock)).debug(any());
                ((doNothing()).when(loggerMock)).error(any());
                ((doNothing()).when(loggerMock)).info(any());
                setStaticField(loggerExampleClazz, "logger", loggerMock);
                mockedStatic = mockStatic(LoggerFactory.class);
                (mockedStatic.when(() -> LoggerFactory.getLogger(any(Class.class)))).thenReturn(loggerMock);
                LoggerExample loggerExample = new LoggerExample();

                int actual = loggerExample.example();

                assertEquals(15, actual);
            } finally {
                setStaticField(LoggerExample.class, "logger", prevLogger);
            }
        } finally {
            mockedStatic.close();
        }
    }

Environment

IntelliJ IDEA

Potential alternatives

Logger is mocked on the step of Symbolic execution.
If mocks are not included in the resulting test - we cannot rely on symbolic execution results.
Generated test cases should be equal to found Symbolic executions.

Possible issues:

• There can be values or method calls inside logger record. And if they are null or throw an exception - the execution will fail.
• Debug/info logger level can be turned off. And is there are logger.debug(...) - there will be exception too.

Context

                Logger loggerMock = mock(Logger.class);
                ((doNothing()).when(loggerMock)).info(any(String.class), any(Object.class));

We have good explanation in User guide

Fuzzer is generating tests without mocks.