Add ITs for validation callback.

src/integrationTest/java/uk/gov/hmcts/probate/controller/DocumentControllerIT.java

@@ -996,6 +996,59 @@ public boolean matches(Object actual) {
         }
     }
 
+    /*
+     * There is no distinction between PP and PA at the point this error occurs. We use PP only because it exists.
+     */
+    @Test
+    void shouldAcceptPdfValidateAmendLegalStatement() throws Exception {
+        String payload = testUtils.getStringFromFile("uploadAmendedLegalStatement_PP.json");
+
+        // unclear why when(sU.gST()).thenReturn("sA"); doesn't work, but this does.
+        doReturn("serviceAuth").when(securityUtils).generateServiceToken();
+
+        final uk.gov.hmcts.reform.ccd.document.am.model.Document mockDocument =
+                uk.gov.hmcts.reform.ccd.document.am.model.Document.builder()
+                        .mimeType(MediaType.APPLICATION_PDF_VALUE)
+                        .build();
+        when(caseDocumentClient.getMetadataForDocument(any(), any(), anyString())).thenReturn(mockDocument);
+
+        final var request = post("/document/validateAmendLegalStatement")
+                .header("authorization", "authToken")
+                .content(payload)
+                .contentType(MediaType.APPLICATION_JSON);
+
+        mockMvc.perform(request)
+                .andExpect(status().isOk());
+    }
+
+    /*
+     * There is no distinction between PP and PA at the point this error occurs. We use PP only because it exists.
+     */
+    @Test
+    void shouldRejectNonPdfValidateAmendLegalStatement() throws Exception {
+        String payload = testUtils.getStringFromFile("uploadAmendedLegalStatement_PP.json");
+
+        // unclear why when(sU.gST()).thenReturn("sA"); doesn't work, but this does.
+        doReturn("serviceAuth").when(securityUtils).generateServiceToken();
+
+        final uk.gov.hmcts.reform.ccd.document.am.model.Document mockDocument =
+                uk.gov.hmcts.reform.ccd.document.am.model.Document.builder()
+                        .mimeType(MediaType.IMAGE_PNG_VALUE)
+                        .build();
+        when(caseDocumentClient.getMetadataForDocument(any(), any(), anyString())).thenReturn(mockDocument);
+
+        final var request = post("/document/validateAmendLegalStatement")
+                .header("authorization", "authToken")
+                .content(payload)
+                .contentType(MediaType.APPLICATION_JSON);
+
+        final RejectedMimeTypeMatcher contentMatcher = new RejectedMimeTypeMatcher(MediaType.IMAGE_PNG_VALUE);
+
+        mockMvc.perform(request)
+                .andExpect(status().isOk())
+                .andExpect(content().string(contentMatcher));
+    }
+
     /*
      * There is no distinction between PP and PA at the point this error occurs. We use PP only because it exists.
      */