tinylog-provider

Mock provider for tinylog

Tinylog provider with a mock instance backed by Mockito.

Warning

This library does not support parallel test execution.

Table of Contents

• Foreword
• How to use
• LoggingProvider as a parameter
• Configuration

Foreword

Unlike the traditional approach where each class or even instance has its own named logger, tinylog uses a singleton logger. And the provider implementation is a bit complicated to check access to the logger. Therefore, I recommend using the Writer for testing.

How to use

Just put a test dependency to your POM:

<dependency>
    <artifactId>mock-loggers-tinylog-provider</artifactId>
    <groupId>io.github.vitalijr2.logging</groupId>
    <scope>test</scope>
    <version>1.2.0</version>
</dependency>

Use the MockTinylogProvider annotation to access the mock provider. The simplest usage example looks like this:

@MockTinylogProvider
private static LoggingProvider logger;

@Test
void helloWorld() {
    when(logger.getMinimumLevel(isNull())).thenReturn(Level.INFO);

    var helloService = new HelloService();

    assertDoesNotThrow(helloService::sayHelloWorld);

    verify(logger).log(anyInt(), isNull(), eq(Level.INFO), isNull(), isNull(), anyString(), isNull());
}

See more details at HelloServiceBasicTest.java

Important

Keep in mind that the logger is initialized only once during the test run.

Therefore, a more complex example cleans the logger after (or before) each test:

// the static logger instance
@MockTinylogProvider
private static LoggingProvider logger;

// clean the mock logger after each test
@AfterEach
void tearDown() {
    clearInvocations(logger);
}

// use the mock logger in a test
@DisplayName("Names")
@ParameterizedTest(name = "<{0}>")
@ValueSource(strings = {"John", "Jane"})
void names(String name) {
    when(logger.getMinimumLevel(isNull())).thenReturn(Level.INFO);

    var helloService = new HelloService();

    assertDoesNotThrow(() -> helloService.sayHello(name));

    verify(logger).log(anyInt(), isNull(), eq(Level.INFO), isNull(), isNull(),
            eq("Hello " + name + "!"), isNull());
}

See more details at HelloServiceFullTest.java

To avoid manual cleaning of the mock logger you can use the jUnit extension for automation:

@ExtendWith(MockLoggerExtension.class)
class HelloServiceExtensionTest {

    @MockTinylogProvider
    private static LoggingProvider logger;

    @DisplayName("Names")
    @ParameterizedTest(name = "<{0}>")
    @ValueSource(strings = {"John", "Jane"})
    void names(String name) {
        when(logger.getMinimumLevel(isNull())).thenReturn(Level.INFO);

        var helloService = new HelloService();

        assertDoesNotThrow(() -> helloService.sayHello(name));

        verify(logger).log(anyInt(), isNull(), eq(Level.INFO), isNull(), isNull(),
                eq("Hello " + name + "!"), isNull());
    }

}

See more details at HelloServiceExtensionTest.java

Also you can use the annotation for automation:

@MockLoggers
class HelloServiceAnnotationTest {

    @MockTinylogProvider
    private static LoggingProvider logger;

    @DisplayName("Names")
    @ParameterizedTest(name = "<{0}>")
    @ValueSource(strings = {"John", "Jane"})
    void names(String name) {
        when(logger.getMinimumLevel(isNull())).thenReturn(Level.INFO);

        var helloService = new HelloService();

        assertDoesNotThrow(() -> helloService.sayHello(name));

        verify(logger).log(anyInt(), isNull(), eq(Level.INFO), isNull(), isNull(),
                eq("Hello " + name + "!"), isNull());
    }

}

See more details at HelloServiceAnnotationTest.java

LoggingProvider as a parameter

This library can also inject a mock provider instance as a parameter of a test method:

@ExtendWith({MockLoggerExtension.class,MockTinylogProviderExtension.class})
class HelloServiceParameterTest {

  @DisplayName("Hello world")
  @Test
  void helloWorld(LoggingProvider logger) {
    when(logger.getMinimumLevel(isNull())).thenReturn(Level.INFO);

    var helloService = new HelloService();

    assertDoesNotThrow(helloService::sayHelloWorld);

    verify(logger).log(anyInt(), isNull(), eq(Level.INFO), isNull(), isNull(), anyString(), isNull());
  }

}

See more details ad HelloServiceParameterTest.java

Configuration

If your application is bundled with another tinylog provider, and it is present on the test classpath, use the configuration to specify the use of the mock provider. See tinylog.properties.