handle no import filter scenario

Author: RIT3shSapata

db/import.go

@@ -552,6 +552,9 @@ func (db *DatabaseCollectionWithUser) ImportFilterDryRun(ctx context.Context, do
 	var shouldImport bool
 	if importFn == "" {
 		importFilter := db.importFilter()
+		if importFilter == nil {
+			return false, base.HTTPErrorf(http.StatusBadRequest, "No import filter specified")
+		}
 		output, err := importFilter.EvaluateFunction(ctx, doc, true)
 		if err != nil {
 			return false, &base.ImportFilterDryRunError{Err: err}

rest/diagnostic_doc_api_test.go

@@ -1411,6 +1411,24 @@ func TestImportFilterDryRun(t *testing.T) {
 			},
 			expectedStatus: http.StatusBadRequest,
 		},
+		{
+			name:            "no_db_import_filter-no_custom_import_filter-no_doc_body-existing_doc-docid",
+			existingDoc:     true,
+			existingDocID:   "no_db_import_filter-no_custom_import_filter-no_doc_body-existing_doc-docid",
+			existingDocBody: `{"user":{"num":125}}`,
+			expectedOutput: ImportFilterDryRun{
+				Error: "Bad Request",
+			},
+			expectedStatus: http.StatusBadRequest,
+		},
+		{
+			name:     "no_db_import_filter-no_custom_import_filter-doc_body-no_existing_doc-no_docid",
+			document: map[string]interface{}{"user": map[string]interface{}{"num": 23}},
+			expectedOutput: ImportFilterDryRun{
+				Error: "Bad Request",
+			},
+			expectedStatus: http.StatusBadRequest,
+		},
 	}
 
 	for _, test := range tests {