Stupid singleton is stupid

00_misuse.java

public class UsesLongRunningCtor {
    /** Retrieves data and returns processed result. */
    public String transformData() {
        // LongRunningCtor "embedded"; direct reference, like a static utility class.
        String rawData = LongRunningCtor.instance().fetch();
        return rawData.replace("Raw", "Processed");
    }
}

01_longrunningctor.java

/** Pseudo-singleton with a slow constructor. Don't make singletons like this. */
public class LongRunningCtor {
    private static final LongRunningCtor INSTANCE = new LongRunningCtor();

    private LongRunningCtor() {
        try { Thread.sleep(60 * 1000); }
        catch (InterruptedException e) { e.printStackTrace(); }
    }

    public String fetch() { return "Raw data"; }

    public static LongRunningCtor instance() { return INSTANCE; }
}

03_slowrunningtest.java

/** Slow test is slow. Calls undecorated singleton. */
@Test
public void testSlowSingleton() {
    long start = System.currentTimeMillis();
    UsesLongRunningCtor underTest = new UsesLongRunningCtor();
    assertEquals("Processed data", underTest.transformData());
    long end = System.currentTimeMillis();
    out.println("Unmocked test time ~" + (end - start) / 1000.0 + " seconds.");
}

// Output is ~ "Unmocked test time ~60.0 seconds."

04_mockoff.java

@RunWith(PowerMockRunner.class)
@PrepareForTest(LongRunningCtor.class)
public class TestWithoutCtor {

    @Test
    public void testSlowSingleton() {
        long start = System.currentTimeMillis();

        // Suppress ctor *before* createPartialMock and static mock, or ctor is run.
        suppress(constructor(LongRunningCtor.class));

        // Could also do mockStaticPartial(LongRunningCtor.class, "instance").
        mockStatic(LongRunningCtor.class);

        // Could also do createPartialMock(LongRunningCtor.class, "fetch").
        LongRunningCtor mock = createMock(LongRunningCtor.class);

        expect(LongRunningCtor.instance()).andReturn(mock);
        expect(mock.fetch()).andReturn("Processed data");

        replayAll(mock);

        UsesLongRunningCtor underTest = new UsesLongRunningCtor();
        assertEquals("Processed data", underTest.transformData());
        long end = System.currentTimeMillis();

        verify(mock);

        out.println("Unmocked test time ~" + (end - start) / 1000.0 + " seconds.");
    }

}

05_pom_fragment.xml

<dependency>
  <groupId>cglib</groupId>
  <artifactId>cglib</artifactId>
  <version>2.2.2</version>
</dependency>

<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.5</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.powermock</groupId>
  <artifactId>powermock-module-junit4</artifactId>
  <version>${powermock.version}</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.powermock</groupId>
  <artifactId>powermock-api-easymock</artifactId>
  <version>${powermock.version}</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.easymock</groupId>
  <artifactId>easymock</artifactId>
  <version>3.1</version>
</dependency>