Add more username tests

These test validate, that no username validation will be performed,
if the form has an error.

src/test/java/catering/users/UserControllerIntegrationTests.java

@@ -61,6 +61,8 @@ class UserControllerIntegrationTests {
 		createTestUser("eva");
 		createTestUser("sarah");
 		createTestUser("paul");
+		createTestUser("maria");
+		createTestUser("adam");
 	}
 
 	@Test
@@ -401,4 +403,45 @@ class UserControllerIntegrationTests {
 				.andExpect(redirectedUrl("/"));
 	}
 
+	@Test
+	@WithMockUser(username = "maria", password = "123")
+	void alreadyExistingNameCheckWillNotBePerformedIfFormHasErrorProfile() throws Exception {
+		assertTrue(userManagement.getUserByName("maria").isPresent());
+		MockHttpServletRequestBuilder createMessage = post("/profile")
+				.param("username", "admin")
+				.param("password", "\0")
+				.param("address", "Baum Straße");
+		assertThat(mvc.perform(createMessage).andReturn().getResponse().getContentAsString())
+				.contains("Ungültiges Passwort")
+				.contains("Ungültiger Name")
+				.doesNotContain("Ungültiger Nutzername");
+	}
+
+	@Test
+	@WithMockUser(username = "admin", password = "admin", roles = "ADMIN")
+	void alreadyExistingNameCheckWillNotBePerformedIfFormHasErrorCustomer() throws Exception {
+		assertThat(userManagement.getUsers().findAll())
+				.extracting("username", "fullName", "address")
+				.contains(tuple("adam", "Adam Klaus", "Baum Weg"));
+		assertThat(mvc.perform(post("/customers/edit/" + userManagement.getUserByName("adam").get().getId())
+				.param("username", "adam")
+				.param("address", "Baum Straße"))
+				.andReturn().getResponse().getContentAsString())
+				.contains("Ungültiger Name")
+				.doesNotContain("Ungültiger Nutzername");
+	}
+
+	@Test
+	@WithAnonymousUser
+	void alreadyExistingNameCheckWillNotBePerformedIfFormHasErrorRegistration() throws Exception {
+		MockHttpServletRequestBuilder createCustomer = post("/register")
+				.param("username", "admin")
+				.param("password", "\0")
+				.param("fullName", "Tom Klaus")
+				.param("address", "Baum Weg");
+		assertThat(mvc.perform(createCustomer).andReturn().getResponse().getContentAsString())
+				.contains("Ungültiges Passwort")
+				.doesNotContain("Ungültiger Nutzername");
+	}
+
 }