Kantis/context-logging

Idiomatic logging using context receivers

Usage

Enable context receivers for your project and add the dependency for the logging framework you're using (TODO: currently only slf4j has been added, but planning to add for kotlin-logging and logback as well)

Gradle

dependencies {
    implementation("io.github.kantis:context-logging-slf4j:0.0.1-SNAPSHOT")
}

Maven

<dependency>
  <groupId>io.github.kantis</groupId>
  <artifactId>context-logging-slf4j-jvm</artifactId>
  <version>0.0.1-SNAPSHOT</version>
</dependency>

Writing logs

Any code which wants to write logs can depend on the LoggingContext which exposes methods for logging.

context(LoggingContext)
fun logHello() {
    info { "Hello" }
}

To create a LoggingContext, send a Slf4jLogger to the LoggingContext constructor.

fun main() {
    with(Slf4jLoggingContext(LoggerFactory.getLogger("my-logger"))) {
        logHello()
    }
}

Testing logging

There's a function called withTestLogging which provides a recording logging context. It results in a List<LogEvent>, for which there's convenient assertions added in the context-logging-kotest-assertions module.

test("verify logging") {
    withTestLogging {
        logHello()
        logHello()
    }.shouldContainExactly(
        LogLevel.INFO("Hello"), // the operator function LogLevel.invoke creates an `ExpectedLogEvent` which the custom assertion uses.
        LogLevel.INFO("Hello"),
    )
}