guava/guava-tests/test/com/google/common/base/StringsTest.java

/*
 * Copyright (C) 2010 The Guava Authors
 *
 * 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 com.google.common.base;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.testing.NullPointerTester;

import junit.framework.TestCase;

/**
 * Unit test for {@link Strings}.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
public class StringsTest extends TestCase {
  public void testNullToEmpty() {
    assertEquals("", Strings.nullToEmpty(null));
    assertEquals("", Strings.nullToEmpty(""));
    assertEquals("a", Strings.nullToEmpty("a"));
  }

  public void testEmptyToNull() {
    assertNull(Strings.emptyToNull(null));
    assertNull(Strings.emptyToNull(""));
    assertEquals("a", Strings.emptyToNull("a"));
  }

  public void testIsNullOrEmpty() {
    assertTrue(Strings.isNullOrEmpty(null));
    assertTrue(Strings.isNullOrEmpty(""));
    assertFalse(Strings.isNullOrEmpty("a"));
  }

  public void testPadStart_noPadding() {
    assertSame("", Strings.padStart("", 0, '-'));
    assertSame("x", Strings.padStart("x", 0, '-'));
    assertSame("x", Strings.padStart("x", 1, '-'));
    assertSame("xx", Strings.padStart("xx", 0, '-'));
    assertSame("xx", Strings.padStart("xx", 2, '-'));
  }

  public void testPadStart_somePadding() {
    assertEquals("-", Strings.padStart("", 1, '-'));
    assertEquals("--", Strings.padStart("", 2, '-'));
    assertEquals("-x", Strings.padStart("x", 2, '-'));
    assertEquals("--x", Strings.padStart("x", 3, '-'));
    assertEquals("-xx", Strings.padStart("xx", 3, '-'));
  }

  public void testPadStart_negativeMinLength() {
    assertSame("x", Strings.padStart("x", -1, '-'));
  }

  // TODO: could remove if we got NPT working in GWT somehow
  public void testPadStart_null() {
    try {
      Strings.padStart(null, 5, '0');
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testPadEnd_noPadding() {
    assertSame("", Strings.padEnd("", 0, '-'));
    assertSame("x", Strings.padEnd("x", 0, '-'));
    assertSame("x", Strings.padEnd("x", 1, '-'));
    assertSame("xx", Strings.padEnd("xx", 0, '-'));
    assertSame("xx", Strings.padEnd("xx", 2, '-'));
  }

  public void testPadEnd_somePadding() {
    assertEquals("-", Strings.padEnd("", 1, '-'));
    assertEquals("--", Strings.padEnd("", 2, '-'));
    assertEquals("x-", Strings.padEnd("x", 2, '-'));
    assertEquals("x--", Strings.padEnd("x", 3, '-'));
    assertEquals("xx-", Strings.padEnd("xx", 3, '-'));
  }

  public void testPadEnd_negativeMinLength() {
    assertSame("x", Strings.padEnd("x", -1, '-'));
  }

  // TODO: could remove if we got NPT working in GWT somehow
  public void testPadEnd_null() {
    try {
      Strings.padEnd(null, 5, '0');
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testRepeat() {
    String input = "20";
    assertEquals("", Strings.repeat(input, 0));
    assertEquals("20", Strings.repeat(input, 1));
    assertEquals("2020", Strings.repeat(input, 2));
    assertEquals("202020", Strings.repeat(input, 3));

    assertEquals("", Strings.repeat("", 4));

    for (int i = 0; i < 100; ++i) {
      assertEquals(2 * i, Strings.repeat(input, i).length());
    }

    try {
      Strings.repeat("x", -1);
      fail();
    } catch (IllegalArgumentException expected) {
    }
    try {
      // Massive string
      Strings.repeat("12345678", (1 << 30) + 3);
      fail();
    } catch (ArrayIndexOutOfBoundsException expected) {
    }
  }

  // TODO: could remove if we got NPT working in GWT somehow
  public void testRepeat_null() {
    try {
      Strings.repeat(null, 5);
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testCommonPrefix() {
    assertEquals("", Strings.commonPrefix("", ""));
    assertEquals("", Strings.commonPrefix("abc", ""));
    assertEquals("", Strings.commonPrefix("", "abc"));
    assertEquals("", Strings.commonPrefix("abcde", "xyz"));
    assertEquals("", Strings.commonPrefix("xyz", "abcde"));
    assertEquals("", Strings.commonPrefix("xyz", "abcxyz"));
    assertEquals("a", Strings.commonPrefix("abc", "aaaaa"));
    assertEquals("aa", Strings.commonPrefix("aa", "aaaaa"));
    assertEquals("abc",
        Strings.commonPrefix(new StringBuffer("abcdef"), "abcxyz"));

    // Identical valid surrogate pairs.
    assertEquals("abc\uD8AB\uDCAB",
        Strings.commonPrefix("abc\uD8AB\uDCABdef", "abc\uD8AB\uDCABxyz"));
    // Differing valid surrogate pairs.
    assertEquals("abc",
        Strings.commonPrefix("abc\uD8AB\uDCABdef", "abc\uD8AB\uDCACxyz"));
    // One invalid pair.
    assertEquals("abc",
        Strings.commonPrefix("abc\uD8AB\uDCABdef", "abc\uD8AB\uD8ABxyz"));
    // Two identical invalid pairs.
    assertEquals("abc\uD8AB\uD8AC",
        Strings.commonPrefix("abc\uD8AB\uD8ACdef", "abc\uD8AB\uD8ACxyz"));
    // Two differing invalid pairs.
    assertEquals("abc\uD8AB",
        Strings.commonPrefix("abc\uD8AB\uD8ABdef", "abc\uD8AB\uD8ACxyz"));
    // One orphan high surrogate.
    assertEquals("", Strings.commonPrefix("\uD8AB\uDCAB", "\uD8AB"));
    // Two orphan high surrogates.
    assertEquals("\uD8AB", Strings.commonPrefix("\uD8AB", "\uD8AB"));
  }

  public void testCommonSuffix() {
    assertEquals("", Strings.commonSuffix("", ""));
    assertEquals("", Strings.commonSuffix("abc", ""));
    assertEquals("", Strings.commonSuffix("", "abc"));
    assertEquals("", Strings.commonSuffix("abcde", "xyz"));
    assertEquals("", Strings.commonSuffix("xyz", "abcde"));
    assertEquals("", Strings.commonSuffix("xyz", "xyzabc"));
    assertEquals("c", Strings.commonSuffix("abc", "ccccc"));
    assertEquals("aa", Strings.commonSuffix("aa", "aaaaa"));
    assertEquals("abc",
        Strings.commonSuffix(new StringBuffer("xyzabc"), "xxxabc"));

    // Identical valid surrogate pairs.
    assertEquals("\uD8AB\uDCABdef",
        Strings.commonSuffix("abc\uD8AB\uDCABdef", "xyz\uD8AB\uDCABdef"));
    // Differing valid surrogate pairs.
    assertEquals("def",
        Strings.commonSuffix("abc\uD8AB\uDCABdef", "abc\uD8AC\uDCABdef"));
    // One invalid pair.
    assertEquals("def",
        Strings.commonSuffix("abc\uD8AB\uDCABdef", "xyz\uDCAB\uDCABdef"));
    // Two identical invalid pairs.
    assertEquals("\uD8AB\uD8ABdef",
        Strings.commonSuffix("abc\uD8AB\uD8ABdef", "xyz\uD8AB\uD8ABdef"));
    // Two differing invalid pairs.
    assertEquals("\uDCABdef",
        Strings.commonSuffix("abc\uDCAB\uDCABdef", "abc\uDCAC\uDCABdef"));
    // One orphan low surrogate.
    assertEquals("", Strings.commonSuffix("x\uD8AB\uDCAB", "\uDCAB"));
    // Two orphan low surrogates.
    assertEquals("\uDCAB", Strings.commonSuffix("\uDCAB", "\uDCAB"));
  }

  public void testValidSurrogatePairAt() {
    assertTrue(Strings.validSurrogatePairAt("\uD8AB\uDCAB", 0));
    assertTrue(Strings.validSurrogatePairAt("abc\uD8AB\uDCAB", 3));
    assertTrue(Strings.validSurrogatePairAt("abc\uD8AB\uDCABxyz", 3));
    assertFalse(Strings.validSurrogatePairAt("\uD8AB\uD8AB", 0));
    assertFalse(Strings.validSurrogatePairAt("\uDCAB\uDCAB", 0));
    assertFalse(Strings.validSurrogatePairAt("\uD8AB\uDCAB", -1));
    assertFalse(Strings.validSurrogatePairAt("\uD8AB\uDCAB", 1));
    assertFalse(Strings.validSurrogatePairAt("\uD8AB\uDCAB", -2));
    assertFalse(Strings.validSurrogatePairAt("\uD8AB\uDCAB", 2));
    assertFalse(Strings.validSurrogatePairAt("x\uDCAB", 0));
    assertFalse(Strings.validSurrogatePairAt("\uD8ABx", 0));
  }

  @GwtIncompatible("NullPointerTester")
  public void testNullPointers() {
    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicStaticMethods(Strings.class);
  }
}