feat(test): Improve unit test coverage

cosid-core/src/test/java/me/ahoo/cosid/cosid/CosIdStateTest.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright [2021-present] [ahoo wang <ahoowang@qq.com> (https://github.com/Ahoo-Wang)].
+ * 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 me.ahoo.cosid.cosid;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CosIdStateTest {
+
+    @Test
+    void testEquals() {
+        CosIdState cosIdState = new CosIdState(0, 0, 0);
+        assertEquals(cosIdState, cosIdState);
+        assertNotEquals(this, cosIdState);
+        CosIdState cosIdState1 = new CosIdState(0, 0, 0);
+        assertEquals(cosIdState, cosIdState1);
+        CosIdState cosIdState2 = new CosIdState(1, 0, 0);
+        assertNotEquals(cosIdState, cosIdState2);
+        CosIdState cosIdState3 = new CosIdState(0, 1, 0);
+        assertNotEquals(cosIdState, cosIdState3);
+        CosIdState cosIdState4 = new CosIdState(0, 0, 1);
+        assertNotEquals(cosIdState, cosIdState4);
+    }
+
+    @Test
+    void testHashCode() {
+        CosIdState cosIdState = new CosIdState(0, 0, 0);
+        assertEquals(cosIdState.hashCode(), cosIdState.hashCode());
+        CosIdState cosIdState1 = new CosIdState(0, 0, 0);
+        assertEquals(cosIdState.hashCode(), cosIdState1.hashCode());
+        CosIdState cosIdState2 = new CosIdState(1, 0, 0);
+        assertNotEquals(cosIdState.hashCode(), cosIdState2.hashCode());
+        CosIdState cosIdState3 = new CosIdState(0, 1, 0);
+        assertNotEquals(cosIdState.hashCode(), cosIdState3.hashCode());
+        CosIdState cosIdState4 = new CosIdState(0, 0, 1);
+        assertNotEquals(cosIdState.hashCode(), cosIdState4.hashCode());
+    }
+
+    @Test
+    void testToString() {
+        CosIdState cosIdState = new CosIdState(0, 0, 0);
+        assertEquals("CosIdState{timestamp=0, machineId=0, sequence=0}", cosIdState.toString());
+    }
+}