test: cover null input behavior in facade API

Author: TamKungZ

src/test/java/me/tamkungz/codecmedia/CodecMediaFacadeTest.java

@@ -12,6 +12,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -84,6 +85,21 @@ void validate_shouldFailWhenFileMissing() throws Exception {
         assertTrue(result.errors().stream().anyMatch(e -> e.contains("does not exist")));
     }
 
+    @Test
+    void validate_shouldFailWhenInputIsNull() throws Exception {
+        CodecMediaEngine engine = CodecMedia.createDefault();
+        var result = engine.validate(null, null);
+        assertFalse(result.valid());
+        assertTrue(result.errors().stream().anyMatch(e -> e.contains("Input file is required")));
+    }
+
+    @Test
+    void probe_shouldRejectNullInputPath() {
+        CodecMediaEngine engine = CodecMedia.createDefault();
+        CodecMediaException ex = assertThrows(CodecMediaException.class, () -> engine.probe(null));
+        assertTrue(ex.getMessage().contains("Input file is required"));
+    }
+
     @Test
     void writeAndReadMetadata_shouldRoundTripViaSidecar() throws Exception {
         CodecMediaEngine engine = CodecMedia.createDefault();