Execute filterData only if data filter is specified. (#83)

Fixed unit tests.

Testing Done:

1. Unit tests pass
2. Added an example sensor. It failed prior to this change. Succeeded after.

Closes #82

controller/signal-filter.go

@@ -91,6 +91,10 @@ func filterContext(expected *v1alpha1.EventContext, actual *v1alpha1.EventContex
 func filterData(dataFilters []*v1alpha1.DataFilter, event *v1alpha1.Event) (bool, error) {
 	// TODO: use the event.Context.SchemaURL to figure out correct data format to unmarshal to
 	// for now, let's just use a simple map[string]interface{} for arbitrary data
+	if dataFilters == nil {
+		return true, nil
+	}
+
 	if event == nil {
 		return false, fmt.Errorf("nil event")
 	}

controller/signal-filter_test.go

@@ -231,14 +231,14 @@ func Test_filterData(t *testing.T) {
 		{
 			name:    "nil event",
 			args:    args{dataFilters: nil, event: nil},
-			want:    false,
-			wantErr: true,
+			want:    true,
+			wantErr: false,
 		},
 		{
 			name:    "unsupported content type",
 			args:    args{dataFilters: nil, event: &v1alpha1.Event{Data: []byte("a")}},
-			want:    false,
-			wantErr: true,
+			want:    true,
+			wantErr: false,
 		},
 		{
 			name: "empty data",

examples/resource-sensor-config-map.yaml

@@ -0,0 +1,40 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Sensor
+metadata:
+  generateName: resource-example-
+  labels:
+    sensors.argoproj.io/controller-instanceid: axis
+spec:
+  signals:
+    - name: config-map-create
+      resource:
+        namespace: default
+        group: ""
+        version: "v1"
+        kind: "ConfigMap"
+        filter:
+          prefix: my-cm
+  triggers:
+    - name: ns-workflow
+      resource:
+        namespace: default
+        group: argoproj.io
+        version: v1alpha1
+        kind: Workflow
+        source:
+          inline: |
+              apiVersion: argoproj.io/v1alpha1
+              kind: Workflow
+              metadata:
+                generateName: hello-world-
+              spec:
+                entrypoint: whalesay
+                templates:
+                  -
+                    container:
+                      args:
+                        - "hello world"
+                      command:
+                        - cowsay
+                      image: "docker/whalesay:latest"
+                    name: whalesay