Test: add unit tests for MetricDataType.checkType()

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

common/transport/mqtt/src/test/java/org/thingsboard/server/transport/mqtt/util/sparkplug/MetricDataTypeTest.java

@@ -0,0 +1,43 @@
+/**
+ * Copyright © 2016-2026 The Thingsboard Authors
+ *
+ * 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 org.thingsboard.server.transport.mqtt.util.sparkplug;
+
+import org.junit.jupiter.api.Test;
+import org.thingsboard.server.common.adaptor.AdaptorException;
+
+import static org.assertj.core.api.Assertions.assertThatNoException;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class MetricDataTypeTest {
+
+    @Test
+    void checkType_noExceptionWhenValueMatchesExpectedType() {
+        assertThatNoException().isThrownBy(() -> MetricDataType.String.checkType("hello"));
+    }
+
+    @Test
+    void checkType_noExceptionWhenValueIsNull() {
+        assertThatNoException().isThrownBy(() -> MetricDataType.String.checkType(null));
+    }
+
+    @Test
+    void checkType_throwsAdaptorExceptionWithActualClassNameWhenTypeMismatch() {
+        assertThatThrownBy(() -> MetricDataType.String.checkType(42))
+                .isInstanceOf(AdaptorException.class)
+                .hasMessageContaining(Integer.class.toString());
+    }
+
+}