edgengramtokenizertest.java

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package org.apache.lucene.analysis.ngram;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

import org.apache.lucene.analysis.Token;

import java.io.StringReader;

import junit.framework.TestCase;

/**
 * Tests {@link EdgeNGramTokenizer} for correctness.
 * @author Otis Gospodnetic
 */
public class EdgeNGramTokenizerTest extends TestCase {
    private StringReader input;
    
    public void setUp() {
        input = new StringReader("abcde");
    }

    public void testInvalidInput() throws Exception {
        boolean gotException = false;
        try {        
            new EdgeNGramTokenizer(input, EdgeNGramTokenizer.Side.FRONT, 0);
        } catch (IllegalArgumentException e) {
            gotException = true;
        }
        assertTrue(gotException);
    }

    public void testInvalidInput2() throws Exception {
        boolean gotException = false;
        try {        
            new EdgeNGramTokenizer(input, EdgeNGramTokenizer.Side.FRONT, -1);
        } catch (IllegalArgumentException e) {
            gotException = true;
        }
        assertTrue(gotException);
    }

    public void testFrontUnigram() throws Exception {
        EdgeNGramTokenizer tokenizer = new EdgeNGramTokenizer(input, EdgeNGramTokenizer.Side.FRONT, 1);
        Token token = null;
        token = tokenizer.next();
        assertEquals("(a,0,1)", token.toString());
        token = tokenizer.next();
        assertNull(token);
    }

    public void testBackUnigram() throws Exception {
        EdgeNGramTokenizer tokenizer = new EdgeNGramTokenizer(input, EdgeNGramTokenizer.Side.BACK, 1);
        Token token = null;
        token = tokenizer.next();
        assertEquals("(e,4,5)", token.toString());
        token = tokenizer.next();
        assertNull(token);
    }

    public void testOversizedNgrams() throws Exception {
        EdgeNGramTokenizer tokenizer = new EdgeNGramTokenizer(input, EdgeNGramTokenizer.Side.FRONT, 6);
        Token token = null;
        token = tokenizer.next();
        assertNull(token);
    }
}