diff --git a/src/test/java/de/retest/web/selenium/css/TransformerTest.java b/src/test/java/de/retest/web/selenium/css/TransformerTest.java
new file mode 100644
index 000000000..59eba1b71
--- /dev/null
+++ b/src/test/java/de/retest/web/selenium/css/TransformerTest.java
@@ -0,0 +1,61 @@
+package de.retest.web.selenium.css;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.when;
+
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.regex.Pattern;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import de.retest.recheck.ui.descriptors.Element;
+
+@ExtendWith( MockitoExtension.class )
+class TransformerTest {
+
+	private static final String SELECTOR_PATTERN = "[a-z;]+";
+	private static final String SELECTED_PART = "abc;";
+	private static final String REMAINING_PART = "b l u b";
+	private static final String TRIMMED_REMAINING_PART = REMAINING_PART.trim();
+	@Mock
+	private Function<String, Predicate<Element>> factory;
+	@Mock
+	private Element element;
+
+	@Test
+	void does_not_match() throws Exception {
+		final Pattern cssPattern = Pattern.compile( "^(" + SELECTOR_PATTERN + ";)(.*)" );
+		final Transformer transformer = new Transformer( cssPattern, factory );
+
+		final String selectorString = "002;blub";
+		final Selector cssSelector = transformer.transform( selectorString );
+
+		assertAll( () -> assertFalse( cssSelector.matches() ),
+				() -> assertFalse( cssSelector.predicate().test( element ) ),
+				() -> assertThat( cssSelector.remainingSelector() ).isEqualTo( selectorString ) );
+	}
+
+	@Test
+	void matches_regex() throws Exception {
+		when( factory.apply( SELECTED_PART ) ).thenReturn( e -> true );
+		final Transformer transformer = newTransformer();
+
+		final Selector cssSelector = transformer.transform( SELECTED_PART + REMAINING_PART );
+
+		assertAll( () -> assertTrue( cssSelector.matches() ),
+				() -> assertTrue( cssSelector.predicate().test( element ) ),
+				() -> assertThat( cssSelector.remainingSelector() ).isEqualTo( TRIMMED_REMAINING_PART ) );
+	}
+
+	private Transformer newTransformer() {
+		final Pattern cssPattern = Pattern.compile( "^(" + SELECTOR_PATTERN + ";)(.*)" );
+		return new Transformer( cssPattern, factory );
+	}
+}