it took me a lot of time but i managed to make to KnobDimmer tests,

now that I kinda understand mockito the next tests should take considerably
less time

src/test/java/ch/usi/inf/sa4/sanmarinoes/smarthut/controller/InputDeviceConnectionControllerTests.java

@@ -0,0 +1,7 @@
+package ch.usi.inf.sa4.sanmarinoes.smarthut.controller;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+@ExtendWith(MockitoExtension.class)
+public class InputDeviceConnectionControllerTests {}

src/test/java/ch/usi/inf/sa4/sanmarinoes/smarthut/controller/KnobDimmerControllerTests.java

@@ -0,0 +1,96 @@
+package ch.usi.inf.sa4.sanmarinoes.smarthut.controller;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.when;
+
+import ch.usi.inf.sa4.sanmarinoes.smarthut.dto.GenericDeviceSaveRequest;
+import ch.usi.inf.sa4.sanmarinoes.smarthut.dto.KnobDimmerDimRequest;
+import ch.usi.inf.sa4.sanmarinoes.smarthut.error.NotFoundException;
+import ch.usi.inf.sa4.sanmarinoes.smarthut.models.*;
+import ch.usi.inf.sa4.sanmarinoes.smarthut.service.DeviceService;
+import java.security.Principal;
+import java.util.Optional;
+import java.util.Set;
+import lombok.SneakyThrows;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.web.context.request.RequestContextHolder;
+import org.springframework.web.context.request.ServletRequestAttributes;
+
+@ExtendWith(MockitoExtension.class)
+@WithMockUser(username = "user")
+@DisplayName("KnobDimmer controller test")
+public class KnobDimmerControllerTests {
+    @InjectMocks private KnobDimmerController controller;
+
+    @Mock private Principal principal;
+
+    @Mock private DeviceService deviceService;
+    @Mock private KnobDimmerRepository knobDimmerRepository;
+
+    @Test
+    public void testGetId() throws NotFoundException {
+        KnobDimmer dimmer = new KnobDimmer();
+        dimmer.setId(42l);
+        when(knobDimmerRepository.findById(42L)).thenReturn(Optional.of(dimmer));
+        when(knobDimmerRepository.findById(1L)).thenReturn(Optional.empty());
+        assertThat(controller.findById(42L)).isSameAs(dimmer);
+        assertThatThrownBy(() -> controller.findById(1L)).isInstanceOf(NotFoundException.class);
+    }
+
+    @Test
+    @SneakyThrows(NotFoundException.class)
+    public void testCreate() {
+        when(principal.getName()).thenReturn("user");
+        doNothing().when(deviceService).throwIfRoomNotOwned(anyLong(), eq("user"));
+        when(deviceService.saveAsOwner(any(KnobDimmer.class), eq("user")))
+                .thenAnswer(i -> i.getArguments()[0]);
+
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        RequestContextHolder.setRequestAttributes(new ServletRequestAttributes(request));
+        GenericDeviceSaveRequest toSend = new GenericDeviceSaveRequest();
+        toSend.setName("dimmer");
+        toSend.setRoomId(42L);
+        KnobDimmer dimmer = controller.create(toSend, principal);
+        assertThat(dimmer.getName()).isEqualTo(toSend.getName());
+        assertThat(dimmer.getRoomId()).isEqualTo(toSend.getRoomId());
+    }
+
+    @Test
+    @SneakyThrows(NotFoundException.class)
+    public void testDelete() {
+        when(principal.getName()).thenReturn("user");
+        doNothing().when(deviceService).deleteByIdAsOwner(eq(42L), eq("user"));
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        RequestContextHolder.setRequestAttributes(new ServletRequestAttributes(request));
+        controller.delete(42L, principal);
+    }
+
+    @Test
+    @SneakyThrows(NotFoundException.class)
+    public void testDimTo() {
+        when(principal.getName()).thenReturn("user");
+        KnobDimmer dimmer = new KnobDimmer();
+        DimmableLight light = new DimmableLight();
+        Curtains curtains = new Curtains();
+        dimmer.addDimmable(light);
+        dimmer.addDimmable(curtains);
+        when(knobDimmerRepository.findByIdAndUsername(42L, "user")).thenReturn(Optional.of(dimmer));
+        KnobDimmerDimRequest toSend = new KnobDimmerDimRequest();
+        toSend.setIntensity(12);
+        toSend.setId(42L);
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        RequestContextHolder.setRequestAttributes(new ServletRequestAttributes(request));
+        Set<Dimmable> set = controller.dimTo(toSend, principal);
+        assertThat(set.size()).isEqualTo(2);
+    }
+}