StringsUtilCapitalizeTest.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.commons.lang3;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNull;
import org.junit.jupiter.api.Test;


public class StringsUtilCapitalizeTest {
      @Test
    void capitalize_NormalLowercaseWord_ReturnsCapitalized() {
        assertEquals("Hello", StringUtils.capitalize("hello"));
    }

    @Test
    void capitalize_AlreadyCapitalizedWord_ReturnsSameString() {
        assertEquals("Hello", StringUtils.capitalize("Hello"));
    }

    @Test
    void capitalize_AllUppercaseWord_ReturnsSameString() {
        assertEquals("HELLO", StringUtils.capitalize("HELLO"));
    }

    @Test
    void capitalize_EmptyString_ReturnsSameString() {
        assertEquals("", StringUtils.capitalize(""));
    }

    @Test
    void capitalize_NullInput_ReturnsNull() {
        assertNull(StringUtils.capitalize(null));
    }

    @Test
    void capitalize_SingleLowercaseChar_ReturnsCapitalizedChar() {
        assertEquals("A", StringUtils.capitalize("a"));
    }

    @Test
    void capitalize_NonLetterFirstChar_ReturnsSameString() {
        assertEquals("1hello", StringUtils.capitalize("1hello"));
    }

    @Test
    void capitalize_WhitespaceOnly_ReturnsSameString() {
        assertEquals("   ", StringUtils.capitalize("   "));
    }
}