Move topology diff to render package.

app/api_topology.go

@@ -7,6 +7,7 @@ import (
 	"github.com/gorilla/mux"
 	"github.com/gorilla/websocket"
 
+	"github.com/weaveworks/scope/render"
 	"github.com/weaveworks/scope/report"
 )
 
@@ -116,7 +117,7 @@ func handleWebsocket(
 	)
 	for {
 		newTopo := t.renderer.Render(rep.Report())
-		diff := report.TopoDiff(previousTopo, newTopo)
+		diff := render.TopoDiff(previousTopo, newTopo)
 		previousTopo = newTopo
 
 		if err := conn.SetWriteDeadline(time.Now().Add(websocketTimeout)); err != nil {

app/api_topology_test.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/gorilla/websocket"
 
+	"github.com/weaveworks/scope/render"
 	"github.com/weaveworks/scope/report"
 )
 
@@ -146,7 +147,7 @@ func TestAPITopologyWebsocket(t *testing.T) {
 
 	_, p, err := ws.ReadMessage()
 	ok(t, err)
-	var d report.Diff
+	var d render.Diff
 	if err := json.Unmarshal(p, &d); err != nil {
 		t.Fatalf("JSON parse error: %s", err)
 	}

render/topology_diff.go

@@ -0,0 +1,41 @@
+package render
+
+import (
+	"reflect"
+
+	"github.com/weaveworks/scope/report"
+)
+
+// Diff is returned by TopoDiff. It represents the changes between two
+// RenderableNode maps.
+type Diff struct {
+	Add    []report.RenderableNode `json:"add"`
+	Update []report.RenderableNode `json:"update"`
+	Remove []string                `json:"remove"`
+}
+
+// TopoDiff gives you the diff to get from A to B.
+func TopoDiff(a, b report.RenderableNodes) Diff {
+	diff := Diff{}
+
+	notSeen := map[string]struct{}{}
+	for k := range a {
+		notSeen[k] = struct{}{}
+	}
+
+	for k, node := range b {
+		if _, ok := a[k]; !ok {
+			diff.Add = append(diff.Add, node)
+		} else if !reflect.DeepEqual(node, a[k]) {
+			diff.Update = append(diff.Update, node)
+		}
+		delete(notSeen, k)
+	}
+
+	// leftover keys
+	for k := range notSeen {
+		diff.Remove = append(diff.Remove, k)
+	}
+
+	return diff
+}

render/topology_diff_test.go

@@ -1,13 +1,22 @@
-package report
+package render
 
 import (
 	"reflect"
 	"sort"
 	"testing"
+
+	"github.com/weaveworks/scope/report"
 )
 
+// ByID is a sort interface for a RenderableNode slice.
+type ByID []report.RenderableNode
+
+func (r ByID) Len() int           { return len(r) }
+func (r ByID) Swap(i, j int)      { r[i], r[j] = r[j], r[i] }
+func (r ByID) Less(i, j int) bool { return r[i].ID < r[j].ID }
+
 func TestTopoDiff(t *testing.T) {
-	nodea := RenderableNode{
+	nodea := report.RenderableNode{
 		ID:         "nodea",
 		LabelMajor: "Node A",
 		LabelMinor: "'ts an a",
@@ -21,14 +30,14 @@ func TestTopoDiff(t *testing.T) {
 		"nodeb",
 		"nodeq", // not the same anymore
 	}
-	nodeb := RenderableNode{
+	nodeb := report.RenderableNode{
 		ID:         "nodeb",
 		LabelMajor: "Node B",
 	}
 
 	// Helper to make RenderableNode maps.
-	nodes := func(ns ...RenderableNode) RenderableNodes {
-		r := RenderableNodes{}
+	nodes := func(ns ...report.RenderableNode) report.RenderableNodes {
+		r := report.RenderableNodes{}
 		for _, n := range ns {
 			r[n.ID] = n
 		}
@@ -43,7 +52,7 @@ func TestTopoDiff(t *testing.T) {
 			label: "basecase: empty -> something",
 			have:  TopoDiff(nodes(), nodes(nodea, nodeb)),
 			want: Diff{
-				Add: []RenderableNode{nodea, nodeb},
+				Add: []report.RenderableNode{nodea, nodeb},
 			},
 		},
 		{
@@ -57,7 +66,7 @@ func TestTopoDiff(t *testing.T) {
 			label: "add and remove",
 			have:  TopoDiff(nodes(nodea), nodes(nodeb)),
 			want: Diff{
-				Add:    []RenderableNode{nodeb},
+				Add:    []report.RenderableNode{nodeb},
 				Remove: []string{"nodea"},
 			},
 		},
@@ -70,7 +79,7 @@ func TestTopoDiff(t *testing.T) {
 			label: "change a single node",
 			have:  TopoDiff(nodes(nodea), nodes(nodeap)),
 			want: Diff{
-				Update: []RenderableNode{nodeap},
+				Update: []report.RenderableNode{nodeap},
 			},
 		},
 	} {
@@ -78,7 +87,7 @@ func TestTopoDiff(t *testing.T) {
 		sort.Sort(ByID(c.have.Add))
 		sort.Sort(ByID(c.have.Update))
 		if !reflect.DeepEqual(c.want, c.have) {
-			t.Errorf("%s - want:%s have:%s", c.label, c.want, c.have)
+			t.Errorf("%s - %s", c.label, diff(c.want, c.have))
 		}
 	}
 }

report/topology.go

@@ -3,7 +3,6 @@ package report
 import (
 	"fmt"
 	"net"
-	"reflect"
 	"strings"
 )
 
@@ -119,47 +118,6 @@ func netsContain(nets []*net.IPNet, ip net.IP) bool {
 	return false
 }
 
-// Diff is returned by TopoDiff. It represents the changes between two
-// RenderableNode maps.
-type Diff struct {
-	Add    []RenderableNode `json:"add"`
-	Update []RenderableNode `json:"update"`
-	Remove []string         `json:"remove"`
-}
-
-// TopoDiff gives you the diff to get from A to B.
-func TopoDiff(a, b RenderableNodes) Diff {
-	diff := Diff{}
-
-	notSeen := map[string]struct{}{}
-	for k := range a {
-		notSeen[k] = struct{}{}
-	}
-
-	for k, node := range b {
-		if _, ok := a[k]; !ok {
-			diff.Add = append(diff.Add, node)
-		} else if !reflect.DeepEqual(node, a[k]) {
-			diff.Update = append(diff.Update, node)
-		}
-		delete(notSeen, k)
-	}
-
-	// leftover keys
-	for k := range notSeen {
-		diff.Remove = append(diff.Remove, k)
-	}
-
-	return diff
-}
-
-// ByID is a sort interface for a RenderableNode slice.
-type ByID []RenderableNode
-
-func (r ByID) Len() int           { return len(r) }
-func (r ByID) Swap(i, j int)      { r[i], r[j] = r[j], r[i] }
-func (r ByID) Less(i, j int) bool { return r[i].ID < r[j].ID }
-
 // Validate checks the topology for various inconsistencies.
 func (t Topology) Validate() error {
 	// Check all edge metadata keys must have the appropriate entries in