Watcher: Fix TransformInput toXContent serialization (elastic/x-pack-elasticsearch#4061)

The toXContent serialization of the transform input was broken, which
could lead to the bad case that a watch could be stored with an invalid
toXContent serialization, that could not be read again, when the watch
should either be executed or even just returned by the Get watch API.

relates elastic/x-pack-elasticsearch#4049

Original commit: elastic/x-pack-elasticsearch@f06ad768b8

plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/input/transform/TransformInput.java

@@ -42,7 +42,7 @@ public class TransformInput implements Input {
 
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-        transform.toXContent(builder, params);
+        builder.startObject().field(transform.type(), transform, params).endObject();
         return builder;
     }
 

plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/input/transform/TransformInputTests.java

@@ -44,7 +44,7 @@ public class TransformInputTests extends ESTestCase {
     private ScriptService scriptService;
 
     @Before
-    public void setupScriptService() throws Exception {
+    public void setupScriptService() {
         Map<String, ScriptEngine> engines = new HashMap<>();
         engines.put(MockScriptEngine.NAME, new MockScriptEngine(MockScriptEngine.NAME, Collections.singletonMap("1", s -> "2")));
         Map<String, ScriptContext<?>> contexts = new HashMap<>();
@@ -54,7 +54,7 @@ public class TransformInputTests extends ESTestCase {
         scriptService = new ScriptService(Settings.EMPTY, engines, contexts);
     }
 
-    public void testExecute() throws Exception {
+    public void testExecute() {
         Script script = new Script(ScriptType.INLINE, MockScriptEngine.NAME, "1", Collections.emptyMap(), Collections.emptyMap());
         ScriptTransform scriptTransform = ScriptTransform.builder(script).build();
         TransformInput transformInput = new TransformInput(scriptTransform);
@@ -110,4 +110,25 @@ public class TransformInputTests extends ESTestCase {
             result.toXContent(builder, ToXContent.EMPTY_PARAMS);
         }
     }
+
+    public void testTransformInputToXContentIsSameAsParsing() throws Exception {
+        Map<String, TransformFactory> transformFactories = Collections.singletonMap("script",
+                new ScriptTransformFactory(Settings.EMPTY, scriptService));
+        TransformRegistry registry = new TransformRegistry(Settings.EMPTY, transformFactories);
+        TransformInputFactory factory = new TransformInputFactory(Settings.EMPTY, registry);
+
+        XContentBuilder jsonBuilder = jsonBuilder().startObject().startObject("script")
+                .field("source", "1")
+                .field("lang", "mockscript")
+                .endObject().endObject();
+        XContentParser parser = createParser(jsonBuilder);
+
+        parser.nextToken();
+        TransformInput transformInput = factory.parseInput("whatever", parser);
+
+        XContentBuilder output = jsonBuilder();
+        transformInput.toXContent(output, ToXContent.EMPTY_PARAMS);
+
+        assertThat(jsonBuilder.string(), is(output.string()));
+    }
 }

qa/smoke-test-watcher-with-painless/src/test/resources/rest-api-spec/test/watcher_painless/10_basic.yml

@@ -13,6 +13,10 @@
               "schedule" : { "cron" : "0 0 0 1 * ? 2099" }
             },
             "input" : {
+              "chain" : {
+                "inputs" : [
+                  {
+                    "first" : {
                       "search" : {
                         "request" : {
                           "indices" : [ "logstash*" ],
@@ -37,6 +41,19 @@
                           }
                         }
                       }
+                    }
+                  },
+                  {
+                    "second" : {
+                      "transform" : {
+                        "script" : {
+                          "source": "return [ 'hits' : [ 'total' : ctx.payload.first.hits.total ]]"
+                        }
+                      }
+                    }
+                  }
+                ]
+              }
             },
             "condition" : {
               "script" : {
@@ -46,6 +63,12 @@
             },
             "actions" : {
               "email_admin" : {
+                "transform" : {
+                  "script" : {
+                    "source" : "return ['foo': 'bar']",
+                    "lang" : "painless"
+                  }
+                },
                 "email" : {
                   "to" : "someone@domain.host.com",
                   "subject" : "404 recently encountered"
@@ -55,6 +78,14 @@
           }
   - match: { _id: "my_exe_watch" }
 
+  - do:
+      xpack.watcher.get_watch:
+        id: "my_exe_watch"
+
+  - match: { _id: "my_exe_watch" }
+  - match: { watch.actions.email_admin.transform.script.source: "return ['foo': 'bar']" }
+  - match: { watch.input.chain.inputs.1.second.transform.script.source: "return [ 'hits' : [ 'total' : ctx.payload.first.hits.total ]]" }
+
   - do:
       xpack.watcher.execute_watch:
         id: "my_exe_watch"