import org.junit.Test;

import static org.junit.Assert.*;

public class LibraryTest {

    @Test
    public void testSomeLibraryMethod() {
        Library classUnderTest = new Library();
        assertTrue("someLibraryMethod should return 'true'", classUnderTest.someLibraryMethod());
    }
}

import org.junit.Test;

import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.*;

public class LibraryTest {

    @Test
    public void testSomeLibraryMethod() {
        assertThat(new Library().someLibraryMethod(), is(true));
    }
}

Use assertThat instead of assertTrue
Use assertThat instead of assertTrue

http://forums.gradle.org/gradle/topics/improvement_ideas_for_the_build_init_plugin
