Mock the Map/Region.clear() operation.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/mock/GemFireMockObjectsSupport.java

@@ -2332,7 +2332,13 @@ public abstract class GemFireMockObjectsSupport extends MockObjectsSupport {
 			return regions.get(subRegionFullPath);
 		});
 
-		// Region.containsKey(key)
+		// Map.clear() / Region.clear()
+		doAnswer(invocation -> {
+			data.clear();
+			return null;
+		}).when(mockRegion).clear();
+
+		// Map.containsKey(key) / Region.containsKey(key)
 		when(mockRegion.containsKey(any())).thenAnswer(invocation ->
 			data.containsKey(invocation.getArgument(0)));
 
@@ -2502,7 +2508,7 @@ public abstract class GemFireMockObjectsSupport extends MockObjectsSupport {
 		});
 
 		// Region.size()
-		when(mockRegion.size()).thenAnswer(invocation -> data.size());
+		doAnswer(invocation -> data.size()).when(mockRegion).size();
 
 		when(mockRegion.subregions(anyBoolean())).thenAnswer(invocation -> {
 

spring-data-geode-test/src/test/java/org/springframework/data/gemfire/tests/MockRegionDataAccessOperationsAndEventsUnitTests.java

@@ -488,4 +488,19 @@ public class MockRegionDataAccessOperationsAndEventsUnitTests {
 		assertThat(this.mockRegion).containsKey(1);
 		assertThat(this.mockRegion.get(1)).isEqualTo("test");
 	}
+
+	@Test
+	public void mapRegionClearIsCorrect() {
+
+		assertThat(this.mockRegion).hasSize(0);
+
+		this.mockRegion.put(1, "TEST");
+		this.mockRegion.put(2, "MOCK");
+
+		assertThat(this.mockRegion).hasSize(2);
+
+		this.mockRegion.clear();
+
+		assertThat(this.mockRegion).hasSize(0);
+	}
 }