CacheTest.java :  » Utilities » antil » antil » cache » Android Open Source

/*
 * Copyright 2011 The Antil Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. 
 */

package antil.cache;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.core.Is.is;
import static org.hamcrest.core.IsNull.notNullValue;
import static org.hamcrest.core.IsNull.nullValue;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

/**
 * @param <T> the type of cache under test.
 */
public abstract class CacheTest<T extends Cache<String, String>> {

    @Rule
    public ExpectedException thrown = ExpectedException.none();

    /**
     * Cache under test.
     */
    protected T cache;

    @Before
    public void setUp() throws Exception {
        cache = createCacheForTesting();
    }

    @Test
    public void clearsCacheWithManyEntries() {
        cache.put("1", "a");
        cache.put("2", "b");
        assertThat(cache.get("1"), is(notNullValue()));

        cache.clear();

        assertThat(cache.get("1"), is(nullValue()));
        assertThat(cache.get("2"), is(nullValue()));
    }

    @Test
    public void clearsCacheWithOneEntry() {
        cache.put("1", "a");
        assertThat(cache.get("1"), is(notNullValue()));

        cache.clear();
        assertThat(cache.get("1"), is(nullValue()));
    }

    @Test
    public void getThrowsExceptionOnNullKey() {
        thrown.expect(NullPointerException.class);
        thrown.expectMessage(exceptionMessageForNullKey());
        cache.get(null);
    }

    @Test
    public void putAssociatesKeysWithValues() {
        cache.put("1", "a");
        cache.put("2", "b");

        assertThat(cache.get("1"), is("a"));
        assertThat(cache.get("2"), is("b"));
    }

    @Test
    public void putAssociatesKeyWithValue() {
        cache.put("1", "a");
        assertThat(cache.get("1"), is("a"));
    }

    @Test
    public void putReplacesOldValueWithNew() {
        cache.put("1", "a");
        cache.put("1", "b");
        assertThat(cache.get("1"), is("b"));
    }

    @Test
    public void putThrowsExceptionOnNullKey() {
        thrown.expect(NullPointerException.class);
        thrown.expectMessage(exceptionMessageForNullKey());
        cache.put(null, "a");
    }

    @Test
    public void putThrowsExceptionOnNullValue() {
        thrown.expect(NullPointerException.class);
        thrown.expectMessage(exceptionMessageForNullValue());
        cache.put("1", null);
    }

    @Test
    public void removesAnEntry() {
        cache.put("1", "a");
        assertThat(cache.get("1"), is(notNullValue()));

        cache.remove("1");
        assertThat(cache.get("1"), is(nullValue()));
    }

    @Test
    public void removeThrowsExceptioOnNullKey() {
        thrown.expect(NullPointerException.class);
        thrown.expectMessage(exceptionMessageForNullKey());
        cache.remove(null);
    }

    @Test
    public void removingAnAbsentKeyIsOk() {
        cache.remove("1"); // No errors
    }

    /**
     * @return a new cache for testing.
     */
    protected abstract T createCacheForTesting();

    /**
     * @return exception message for a <code>null</code> key.
     */
    protected String exceptionMessageForNullKey() {
        return "Key cannot be null";
    }

    /**
     * @return exception message for a <code>null</code> value.
     */
    protected String exceptionMessageForNullValue() {
        return "Value cannot be null";
    }
}