diff --git a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/exception/NotFiniteNumberExceptionTest.java b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/exception/NotFiniteNumberExceptionTest.java
new file mode 100644
index 000000000..e5a3f5410
--- /dev/null
+++ b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/exception/NotFiniteNumberExceptionTest.java
@@ -0,0 +1,68 @@
+/*
+ * 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.math4.legacy.exception;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;
+
+/**
+ * Tests for {@link NotFiniteNumberException}.
+ */
+public final class NotFiniteNumberExceptionTest {
+    @Test
+    public void testCheckSingle() {
+        try {
+            NotFiniteNumberException.check(Double.POSITIVE_INFINITY);
+            Assert.fail("an exception should have been thrown");
+        } catch (NotFiniteNumberException e) {
+            // Expected
+        }
+        try {
+            NotFiniteNumberException.check(Double.NEGATIVE_INFINITY);
+            Assert.fail("an exception should have been thrown");
+        } catch (NotFiniteNumberException e) {
+            // Expected
+        }
+        try {
+            NotFiniteNumberException.check(Double.NaN);
+            Assert.fail("an exception should have been thrown");
+        } catch (NotFiniteNumberException e) {
+            // Expected
+        }
+    }
+
+    @Test
+    public void testCheckArray() {
+        try {
+            NotFiniteNumberException.check(new double[] {0, -1, Double.POSITIVE_INFINITY, -2, 3});
+            Assert.fail("an exception should have been thrown");
+        } catch (NotFiniteNumberException e) {
+            // Expected
+        }
+        try {
+            NotFiniteNumberException.check(new double[] {1, Double.NEGATIVE_INFINITY, -2, 3});
+            Assert.fail("an exception should have been thrown");
+        } catch (NotFiniteNumberException e) {
+            // Expected
+        }
+        try {
+            NotFiniteNumberException.check(new double[] {4, 3, -1, Double.NaN, -2, 1});
+            Assert.fail("an exception should have been thrown");
+        } catch (NotFiniteNumberException e) {
+            // Expected
+        }
+    }
+}
diff --git a/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/exception/NullArgumentExceptionTest.java b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/exception/NullArgumentExceptionTest.java
new file mode 100644
index 000000000..6dd73be97
--- /dev/null
+++ b/commons-math-legacy/src/test/java/org/apache/commons/math4/legacy/exception/NullArgumentExceptionTest.java
@@ -0,0 +1,44 @@
+/*
+ * 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.math4.legacy.exception;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import org.apache.commons.math4.legacy.exception.util.LocalizedFormats;
+
+/**
+ * Tests for {@link NullArgumentException}.
+ */
+public final class NullArgumentExceptionTest {
+    @Test
+    public void testCheckSingle() {
+        try {
+            Object obj = null;
+            NullArgumentException.check(obj);
+        } catch (NullArgumentException e) {
+            // Expected.
+        }
+    }
+
+    @Test
+    public void testCheckArray() {
+        try {
+            double[] array = null;
+            NullArgumentException.check(array, LocalizedFormats.INPUT_ARRAY);
+        } catch (NullArgumentException e) {
+            // Expected.
+        }
+    }
+}