diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java
index 9a85b06..2fc6a0c 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/BigDecimalsTests.java
@@ -27,8 +27,6 @@ import lombok.extern.slf4j.Slf4j;
 @Slf4j
 public class BigDecimalsTests {
 
-    // TODO 【优化】 检查测试用例
-
     @Test
     void equalsValue_NullValues_ReturnsTrue() {
         assertTrue(BigDecimals.equalsValue(null, null));
@@ -176,7 +174,8 @@ public class BigDecimalsTests {
         BigDecimal bd1 = new BigDecimal("10");
         BigDecimal bd2 = new BigDecimal("20");
         BigDecimal bd3 = new BigDecimal("30");
-        assertEquals(new BigDecimal("60"), BigDecimals.sum(bd1, bd2, bd3));
+        BigDecimal bd4 = null;
+        assertEquals(new BigDecimal("60"), BigDecimals.sum(bd1, bd2, bd3, bd4));
     }
 
     @Test
@@ -192,6 +191,8 @@ public class BigDecimalsTests {
 
     @Test
     void of_BlankString_ReturnsZero() {
+        assertEquals(BigDecimal.ZERO, BigDecimals.of(null));
+        assertEquals(BigDecimal.ZERO, BigDecimals.of(""));
         assertEquals(BigDecimal.ZERO, BigDecimals.of(" "));
     }
 
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/NumbersTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/NumbersTests.java
index d09300f..1e2435f 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/NumbersTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/NumbersTests.java
@@ -24,8 +24,6 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 public
 class NumbersTests {
 
-    // TODO 【优化】 检查测试用例
-
     @Test
     public void sum_ShortArray_ReturnsCorrectSum() {
         short[] numbers = {1, 2, 3, 4};
diff --git a/src/test/java/xyz/zhouxy/plusone/commons/util/OptionalToolsTests.java b/src/test/java/xyz/zhouxy/plusone/commons/util/OptionalToolsTests.java
index 47ba4db..79199e4 100644
--- a/src/test/java/xyz/zhouxy/plusone/commons/util/OptionalToolsTests.java
+++ b/src/test/java/xyz/zhouxy/plusone/commons/util/OptionalToolsTests.java
@@ -19,6 +19,7 @@ package xyz.zhouxy.plusone.commons.util;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.Optional;
@@ -28,11 +29,12 @@ import java.util.OptionalLong;
 
 import org.junit.jupiter.api.Test;
 
+/**
+ * {@link OptionalTools} 单元测试
+ */
 public
 class OptionalToolsTests {
 
-    // TODO 【优化】 检查测试用例
-
     @Test
     void optionalOf_NullInteger_ReturnsEmptyOptionalInt() {
         OptionalInt result = OptionalTools.optionalOf((Integer) null);
@@ -112,8 +114,14 @@ class OptionalToolsTests {
     }
 
     @Test
-    void orElseNull_NullOptional_ReturnsNull() {
-        Object result = OptionalTools.orElseNull(Optional.ofNullable(null));
+    void orElseNull_NullOptional_ThrowsNullPointerException() {
+        assertThrows(NullPointerException.class,
+                () -> OptionalTools.orElseNull(null));
+    }
+
+    @Test
+    void orElseNull_EmptyOptional_ReturnsNull() {
+        Object result = OptionalTools.orElseNull(Optional.empty());
         assertNull(result);
     }
 
@@ -124,7 +132,13 @@ class OptionalToolsTests {
     }
 
     @Test
-    void toInteger_NullOptionalInt_ReturnsNull() {
+    void toInteger_NullOptionalInt_ThrowsNullPointerException() {
+        assertThrows(NullPointerException.class,
+                () -> OptionalTools.toInteger(null));
+    }
+
+    @Test
+    void toInteger_EmptyOptionalInt_ReturnsNull() {
         Integer result = OptionalTools.toInteger(OptionalInt.empty());
         assertNull(result);
     }
@@ -136,7 +150,13 @@ class OptionalToolsTests {
     }
 
     @Test
-    void toLong_NullOptionalLong_ReturnsNull() {
+    void toLong_NullOptionalLong_ThrowsNullPointerException() {
+        assertThrows(NullPointerException.class,
+                () -> OptionalTools.toLong(null));
+    }
+
+    @Test
+    void toLong_EmptyOptionalLong_ReturnsNull() {
         Long result = OptionalTools.toLong(OptionalLong.empty());
         assertNull(result);
     }
@@ -148,7 +168,13 @@ class OptionalToolsTests {
     }
 
     @Test
-    void toDouble_NullOptionalDouble_ReturnsNull() {
+    void toDouble_NullOptionalDouble_ThrowsNullPointerException() {
+        assertThrows(NullPointerException.class,
+                () -> OptionalTools.toDouble(null));
+    }
+
+    @Test
+    void toDouble_EmptyOptionalDouble_ReturnsNull() {
         Double result = OptionalTools.toDouble(OptionalDouble.empty());
         assertNull(result);
     }