Transformer transformer1 = mock(Transformer.class);
when(transformer1.transform(any(Object.class))).thenReturn(null);
when(transformer1.isSourceDataTypeSupported(any(DataType.class))).thenReturn(true);
Transformer transformer2 = mock(Transformer.class);
when(transformer2.transform(any(Object.class))).thenReturn("foo");
when(transformer2.isSourceDataTypeSupported(any(DataType.class))).thenReturn(true);
DefaultMuleMessage message = new DefaultMuleMessage(null, muleContext);
message.applyTransformers(null, transformer1, transformer2);