Temporal Coupling Example

TestsExecutionRecorderBad.java

public class TestsExecutionRecorder {

    private String namespace;
    private Stopwatch stopwatch;
    private long duration;

    TestsExecutionRecorder(TestType testType) {
        this.namespace = "test." + testType;
    }

    // MUST be called before testEnvLoadEnded()
    public void startRecording() {
        DevMetricReporter.reportMetric(namespace + ".execution.counter", 1);
        this.stopwatch = Stopwatch.createStarted();
    }

    // CAN be called before testEnvLoadEnded() - meaningless if called after it
    public void setGroupName(String groupName) {
        this.namespace += "." + groupName;
    }

    // MUST be called after startRecording()
    public void testEnvLoadEnded() {
        this.duration = stopwatch.elapsed(TimeUnit.SECONDS);
        storeRecord();
    }

    private void storeRecord() {
        DevMetricReporter.reportMetric(this.namespace + ".execution.loadDuration", this.duration);
    }
}

// USAGE:
final TestsExecutionRecorder testsExecutionRecorder = new TestsExecutionRecorder(TestType.Integration);
// more stuff...
testsExecutionRecorder.startRecording();
// more code that may take a while...
final Optional<String> groupName = getGroupName();
groupName.ifPresent(testsExecutionRecorder::setGroupName);
// more code that may take a while...
testsExecutionRecorder.testEnvLoadEnded();

TestsExecutionRecorderBetter.java

public class TestsExecutionRecorder {

    // no mutable fields
    private final String namespace;
    private final Stopwatch stopwatch;

    TestsExecutionRecorder(TestType testType) {
        namespace = "test." + testType;
        DevMetricReporter.reportMetric(namespace + ".execution.counter", 1);
        stopwatch = Stopwatch.createStarted();
    }

    // only one public method
    public void testEnvLoadEnded(Optional<String> groupName) {
        final long duration = stopwatch.elapsed(TimeUnit.SECONDS);
        final String prefix = groupName.map(g -> namespace + "." + g).orElse(namespace);
        DevMetricReporter.reportMetric(prefix + ".execution.loadDuration", duration);
    }
}

// USAGE:
// more stuff...
final TestsExecutionRecorder testsExecutionRecorder = new TestsExecutionRecorder(TestType.Integration);
// more code that may take a while...
final Optional<String> groupName = getGroupName();
// more code that may take a while...
testsExecutionRecorder.testEnvLoadEnded(groupName);