MXS-1999: Fix removal of undefined relationships

If a relationship isn't defined, it should not be removed. Only if a
relationship is change to a null relationship, should it be removed.

Also fixed the maxctrl test suite to verify that both it and the REST API
tests pass.

server/core/config_runtime.cc

@@ -1385,7 +1385,8 @@ SERVER* runtime_create_server_from_json(json_t* json)
 
 bool server_to_object_relations(SERVER* server, json_t* old_json, json_t* new_json)
 {
-    if (mxs_json_pointer(new_json, MXS_JSON_PTR_RELATIONSHIPS) == NULL)
+    if (mxs_json_pointer(new_json, MXS_JSON_PTR_RELATIONSHIPS_SERVICES) == NULL &&
+        mxs_json_pointer(new_json, MXS_JSON_PTR_RELATIONSHIPS_MONITORS) == NULL)
     {
         /** No change to relationships */
         return true;
@@ -1633,7 +1634,7 @@ MXS_MONITOR* runtime_create_monitor_from_json(json_t* json)
 
 bool object_to_server_relations(const char* target, json_t* old_json, json_t* new_json)
 {
-    if (mxs_json_pointer(new_json, MXS_JSON_PTR_RELATIONSHIPS) == NULL)
+    if (mxs_json_pointer(new_json, MXS_JSON_PTR_RELATIONSHIPS_SERVERS) == NULL)
     {
         /** No change to relationships */
         return true;

server/core/test/rest-api/test/monitor.js

@@ -57,6 +57,15 @@ describe("Monitor Relationships", function() {
             })
     });
 
+    it("missing relationships are not removed", function() {
+        var mon = {data: {relationships: {}}}
+        return request.patch(base_url + "/monitors/MariaDB-Monitor", {json: mon})
+        .then(() => request.get(base_url + "/monitors/MariaDB-Monitor", { json: true }))
+        .then((res) => {
+            res.data.relationships.should.have.keys("servers")
+        })
+    });
+
     it("remove relationships from old monitor", function() {
         var mon = {data: {relationships: {servers: {data: null}}}}
         return request.patch(base_url + "/monitors/MariaDB-Monitor", {json: mon})

server/core/test/rest-api/test/server.js

@@ -101,6 +101,20 @@ describe("Server Relationships", function() {
         rel_server.data.relationships["monitors"] = null
         return request.patch(base_url + "/servers/" + rel_server.data.id, {json: rel_server})
             .should.be.rejected
+            .then(() => request.get(base_url + "/servers/" + rel_server.data.id, {json: true}))
+            .then((res) => {
+                res.data.relationships.should.have.keys("services")
+            })
+    });
+
+    it("missing relationships are not removed", function() {
+        rel_server.data.relationships = {}
+        return request.patch(base_url + "/servers/" + rel_server.data.id, {json: rel_server})
+            .should.be.fulfilled
+            .then(() => request.get(base_url + "/servers/" + rel_server.data.id, {json: true}))
+            .then((res) => {
+                res.data.relationships.should.have.keys("services")
+            })
     });
 
     it("remove relationships", function() {
@@ -108,6 +122,11 @@ describe("Server Relationships", function() {
         rel_server.data.relationships["monitors"] = {data: null}
         return request.patch(base_url + "/servers/" + rel_server.data.id, {json: rel_server})
             .should.be.fulfilled
+            .then(() => request.get(base_url + "/servers/" + rel_server.data.id, {json: true}))
+            .then((res) => {
+                res.data.relationships.should.not.have.keys("services")
+                res.data.relationships.should.not.have.keys("monitors")
+            })
     });
 
     it("destroy server", function() {

server/core/test/rest-api/test/service.js

@@ -20,12 +20,27 @@ describe("Service", function() {
     });
 
 
-    it("remove service relationship", function() {
+    it("missing relationships are not removed", function() {
         return request.get(base_url + "/services/RW-Split-Router")
             .then(function(resp) {
                 var svc = JSON.parse(resp)
                 delete svc.data.relationships["servers"]
-                delete svc.data.relationships["servers"]
+                return request.patch(base_url + "/services/RW-Split-Router", {json: svc})
+            })
+            .then(function(resp) {
+                return request.get(base_url + "/services/RW-Split-Router")
+            })
+            .then(function(resp) {
+                var svc = JSON.parse(resp)
+                svc.data.relationships.should.not.be.empty
+            })
+    });
+
+    it("remove service relationship", function() {
+        return request.get(base_url + "/services/RW-Split-Router")
+            .then(function(resp) {
+                var svc = JSON.parse(resp)
+                svc.data.relationships.servers.data = null
                 return request.patch(base_url + "/services/RW-Split-Router", {json: svc})
             })
             .then(function(resp) {

test/run_npm_test.sh

@@ -27,6 +27,9 @@ cp -t $testdir -r $srcdir/test/*
 # Copy test sources to test workspace
 cp -t $testdir -r $testsrc/*
 
+# Required by MaxCtrl (not super pretty)
+cp -t $testdir/.. $srcdir/VERSION*.cmake
+
 # Copy required docker-compose files to the MaxScale directory and bring MariaDB
 # servers up. This is an asynchronous process.
 cd $maxscaledir