Add unit tests for me.zhengjie.utils.StringUtils

These tests were written using Diffblue Cover.

eladmin-common/src/test/java/me/zhengjie/utils/StringUtilsTest.java

+package me.zhengjie.utils;
+
+import org.junit.Test;
+import org.springframework.mock.web.MockHttpServletRequest;
+
+import java.text.SimpleDateFormat;
+import java.util.*;
+
+import static me.zhengjie.utils.StringUtils.*;
+import static org.junit.Assert.*;
+
+public class StringUtilsTest {
+
+    @Test
+    public void testInString() {
+        assertTrue(inString("?", "?"));
+        assertFalse(inString("?", new String[]{}));
+    }
+
+    @Test
+    public void testToCamelCase() {
+        assertNull(toCamelCase(null));
+    }
+
+    @Test
+    public void testToCapitalizeCamelCase() {
+        assertNull(StringUtils.toCapitalizeCamelCase(null));
+        assertEquals("HelloWorld", toCapitalizeCamelCase("hello_world"));
+    }
+
+    @Test
+    public void testToUnderScoreCase() {
+        assertNull(StringUtils.toUnderScoreCase(null));
+        assertEquals("hello_world", toUnderScoreCase("helloWorld"));
+        assertEquals("\u0000\u0000", toUnderScoreCase("\u0000\u0000"));
+        assertEquals("\u0000_a", toUnderScoreCase("\u0000A"));
+    }
+
+    @Test
+    public void testGetWeekDay() {
+        SimpleDateFormat simpleDateformat = new SimpleDateFormat("E");
+        assertEquals(simpleDateformat.format(new Date()), getWeekDay());
+    }
+
+    @Test
+    public void testGetIP() {
+        assertEquals("127.0.0.1", getIP(new MockHttpServletRequest()));
+    }
+}