lucene/analysis/common/src/test/org/apache/lucene/analysis/shingle/TestShingleFilterFactory.java

/*
 * 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.
 */
package org.apache.lucene.analysis.shingle;

import java.io.Reader;
import java.io.StringReader;
import org.apache.lucene.analysis.BaseTokenStreamFactoryTestCase;
import org.apache.lucene.analysis.TokenStream;

/** Simple tests to ensure the Shingle filter factory works. */
public class TestShingleFilterFactory extends BaseTokenStreamFactoryTestCase {
  /** Test the defaults */
  public void testDefaults() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream = tokenFilterFactory("Shingle").create(stream);
    assertTokenStreamContents(
        stream, new String[] {"this", "this is", "is", "is a", "a", "a test", "test"});
  }

  /** Test with unigrams disabled */
  public void testNoUnigrams() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream = tokenFilterFactory("Shingle", "outputUnigrams", "false").create(stream);
    assertTokenStreamContents(stream, new String[] {"this is", "is a", "a test"});
  }

  /** Test with a higher max shingle size */
  public void testMaxShingleSize() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream = tokenFilterFactory("Shingle", "maxShingleSize", "3").create(stream);
    assertTokenStreamContents(
        stream,
        new String[] {
          "this", "this is", "this is a", "is", "is a", "is a test", "a", "a test", "test"
        });
  }

  /** Test with higher min (and max) shingle size */
  public void testMinShingleSize() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory("Shingle", "minShingleSize", "3", "maxShingleSize", "4").create(stream);
    assertTokenStreamContents(
        stream,
        new String[] {"this", "this is a", "this is a test", "is", "is a test", "a", "test"});
  }

  /** Test with higher min (and max) shingle size and with unigrams disabled */
  public void testMinShingleSizeNoUnigrams() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory(
                "Shingle", "minShingleSize", "3", "maxShingleSize", "4", "outputUnigrams", "false")
            .create(stream);
    assertTokenStreamContents(stream, new String[] {"this is a", "this is a test", "is a test"});
  }

  /** Test with higher same min and max shingle size */
  public void testEqualMinAndMaxShingleSize() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory("Shingle", "minShingleSize", "3", "maxShingleSize", "3").create(stream);
    assertTokenStreamContents(
        stream, new String[] {"this", "this is a", "is", "is a test", "a", "test"});
  }

  /** Test with higher same min and max shingle size and with unigrams disabled */
  public void testEqualMinAndMaxShingleSizeNoUnigrams() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory(
                "Shingle", "minShingleSize", "3", "maxShingleSize", "3", "outputUnigrams", "false")
            .create(stream);
    assertTokenStreamContents(stream, new String[] {"this is a", "is a test"});
  }

  /** Test with a non-default token separator */
  public void testTokenSeparator() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream = tokenFilterFactory("Shingle", "tokenSeparator", "=BLAH=").create(stream);
    assertTokenStreamContents(
        stream,
        new String[] {"this", "this=BLAH=is", "is", "is=BLAH=a", "a", "a=BLAH=test", "test"});
  }

  /** Test with a non-default token separator and with unigrams disabled */
  public void testTokenSeparatorNoUnigrams() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory("Shingle", "tokenSeparator", "=BLAH=", "outputUnigrams", "false")
            .create(stream);
    assertTokenStreamContents(stream, new String[] {"this=BLAH=is", "is=BLAH=a", "a=BLAH=test"});
  }

  /** Test with an empty token separator */
  public void testEmptyTokenSeparator() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream = tokenFilterFactory("Shingle", "tokenSeparator", "").create(stream);
    assertTokenStreamContents(
        stream, new String[] {"this", "thisis", "is", "isa", "a", "atest", "test"});
  }

  /** Test with higher min (and max) shingle size and with a non-default token separator */
  public void testMinShingleSizeAndTokenSeparator() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory(
                "Shingle", "minShingleSize", "3", "maxShingleSize", "4", "tokenSeparator", "=BLAH=")
            .create(stream);
    assertTokenStreamContents(
        stream,
        new String[] {
          "this",
          "this=BLAH=is=BLAH=a",
          "this=BLAH=is=BLAH=a=BLAH=test",
          "is",
          "is=BLAH=a=BLAH=test",
          "a",
          "test"
        });
  }

  /**
   * Test with higher min (and max) shingle size and with a non-default token separator and with
   * unigrams disabled
   */
  public void testMinShingleSizeAndTokenSeparatorNoUnigrams() throws Exception {
    Reader reader = new StringReader("this is a test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory(
                "Shingle",
                "minShingleSize",
                "3",
                "maxShingleSize",
                "4",
                "tokenSeparator",
                "=BLAH=",
                "outputUnigrams",
                "false")
            .create(stream);
    assertTokenStreamContents(
        stream,
        new String[] {
          "this=BLAH=is=BLAH=a", "this=BLAH=is=BLAH=a=BLAH=test", "is=BLAH=a=BLAH=test",
        });
  }

  /**
   * Test with unigrams disabled except when there are no shingles, with a single input token. Using
   * default min/max shingle sizes: 2/2. No shingles will be created, since there are fewer input
   * tokens than min shingle size. However, because outputUnigramsIfNoShingles is set to true, even
   * though outputUnigrams is set to false, one unigram should be output.
   */
  public void testOutputUnigramsIfNoShingles() throws Exception {
    Reader reader = new StringReader("test");
    TokenStream stream = whitespaceMockTokenizer(reader);
    stream =
        tokenFilterFactory(
                "Shingle", "outputUnigrams", "false", "outputUnigramsIfNoShingles", "true")
            .create(stream);
    assertTokenStreamContents(stream, new String[] {"test"});
  }

  /** Test that bogus arguments result in exception */
  public void testBogusArguments() throws Exception {
    IllegalArgumentException expected =
        expectThrows(
            IllegalArgumentException.class,
            () -> {
              tokenFilterFactory("Shingle", "bogusArg", "bogusValue");
            });
    assertTrue(expected.getMessage().contains("Unknown parameters"));
  }
}