Moves conversion of nil slices up to HTTP layer for prepared queries.

command/agent/prepared_query_endpoint.go

@@ -54,6 +54,11 @@ func (s *HTTPServer) PreparedQueryGeneral(resp http.ResponseWriter, req *http.Re
 		if err := s.agent.RPC(endpoint+".List", &args, &reply); err != nil {
 			return nil, err
 		}
+
+		// Use empty list instead of nil.
+		if reply.Queries == nil {
+			reply.Queries = make(structs.PreparedQueries, 0)
+		}
 		return reply.Queries, nil
 
 	default:
@@ -111,6 +116,11 @@ func (s *HTTPServer) PreparedQuerySpecific(resp http.ResponseWriter, req *http.R
 				}
 				return nil, err
 			}
+
+			// Use empty list instead of nil.
+			if reply.Nodes == nil {
+				reply.Nodes = make(structs.CheckServiceNodes, 0)
+			}
 			return reply, nil
 		} else {
 			args := structs.PreparedQuerySpecificRequest{

command/agent/prepared_query_endpoint_test.go

@@ -144,6 +144,40 @@ func TestPreparedQuery_Create(t *testing.T) {
 }
 
 func TestPreparedQuery_List(t *testing.T) {
+	httpTest(t, func(srv *HTTPServer) {
+		m := MockPreparedQuery{}
+		if err := srv.agent.InjectEndpoint("PreparedQuery", &m); err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		m.listFn = func(args *structs.DCSpecificRequest, reply *structs.IndexedPreparedQueries) error {
+			// Return an empty response.
+			return nil
+		}
+
+		body := bytes.NewBuffer(nil)
+		req, err := http.NewRequest("GET", "/v1/query", body)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		resp := httptest.NewRecorder()
+		obj, err := srv.PreparedQueryGeneral(resp, req)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if resp.Code != 200 {
+			t.Fatalf("bad code: %d", resp.Code)
+		}
+		r, ok := obj.(structs.PreparedQueries)
+		if !ok {
+			t.Fatalf("unexpected: %T", obj)
+		}
+		if r == nil || len(r) != 0 {
+			t.Fatalf("bad: %v", r)
+		}
+	})
+
 	httpTest(t, func(srv *HTTPServer) {
 		m := MockPreparedQuery{}
 		if err := srv.agent.InjectEndpoint("PreparedQuery", &m); err != nil {
@@ -194,6 +228,40 @@ func TestPreparedQuery_List(t *testing.T) {
 }
 
 func TestPreparedQuery_Execute(t *testing.T) {
+	httpTest(t, func(srv *HTTPServer) {
+		m := MockPreparedQuery{}
+		if err := srv.agent.InjectEndpoint("PreparedQuery", &m); err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		m.executeFn = func(args *structs.PreparedQueryExecuteRequest, reply *structs.PreparedQueryExecuteResponse) error {
+			// Just return an empty response.
+			return nil
+		}
+
+		body := bytes.NewBuffer(nil)
+		req, err := http.NewRequest("GET", "/v1/query/my-id/execute", body)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		resp := httptest.NewRecorder()
+		obj, err := srv.PreparedQuerySpecific(resp, req)
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+		if resp.Code != 200 {
+			t.Fatalf("bad code: %d", resp.Code)
+		}
+		r, ok := obj.(structs.PreparedQueryExecuteResponse)
+		if !ok {
+			t.Fatalf("unexpected: %T", obj)
+		}
+		if r.Nodes == nil || len(r.Nodes) != 0 {
+			t.Fatalf("bad: %v", r)
+		}
+	})
+
 	httpTest(t, func(srv *HTTPServer) {
 		m := MockPreparedQuery{}
 		if err := srv.agent.InjectEndpoint("PreparedQuery", &m); err != nil {

consul/state/prepared_query.go

@@ -243,7 +243,7 @@ func (s *StateStore) PreparedQueryList() (uint64, structs.PreparedQueries, error
 	}
 
 	// Go over all of the queries and build the response.
-	result := make(structs.PreparedQueries, 0)
+	var result structs.PreparedQueries
 	for query := queries.Next(); query != nil; query = queries.Next() {
 		result = append(result, query.(*structs.PreparedQuery))
 	}

consul/state/prepared_query_test.go

@@ -379,7 +379,7 @@ func TestStateStore_PreparedQueryLookup(t *testing.T) {
 func TestStateStore_PreparedQueryList(t *testing.T) {
 	s := testStateStore(t)
 
-	// Make sure an empty (non-nil) slice is returned if there are no queries.
+	// Make sure nothing is returned for an empty query
 	idx, actual, err := s.PreparedQueryList()
 	if err != nil {
 		t.Fatalf("err: %s", err)
@@ -387,7 +387,7 @@ func TestStateStore_PreparedQueryList(t *testing.T) {
 	if idx != 0 {
 		t.Fatalf("bad index: %d", idx)
 	}
-	if actual == nil || len(actual) != 0 {
+	if len(actual) != 0 {
 		t.Fatalf("bad: %v", actual)
 	}