topWalk tests

engine/drawdag_test.go

@@ -81,3 +81,108 @@ func TestDAGAddVertex(t *testing.T) {
 		t.Errorf("diff after adding vertex u a second time:\n%s", diff)
 	}
 }
+
+func TestDAGRemoveVertex(t *testing.T) {
+	u := fakeDrawBoxer("u")
+	v := fakeDrawBoxer("v")
+	w := fakeDrawBoxer("w")
+	d := dag{
+		u: edges{
+			in:  drawerSet{},
+			out: drawerSet{v: {}},
+		},
+		v: edges{
+			in:  drawerSet{u: {}},
+			out: drawerSet{w: {}},
+		},
+		w: edges{
+			in:  drawerSet{v: {}},
+			out: drawerSet{},
+		},
+	}
+	d.removeVertex(u)
+	want := dag{
+		v: edges{
+			in:  drawerSet{},
+			out: drawerSet{w: {}},
+		},
+		w: edges{
+			in:  drawerSet{v: {}},
+			out: drawerSet{},
+		},
+	}
+	if diff := cmp.Diff(d, want, cmp.AllowUnexported(edges{})); diff != "" {
+		t.Errorf("diff after removing vertex u:\n%s", diff)
+	}
+	d.removeVertex(u)
+	if diff := cmp.Diff(d, want, cmp.AllowUnexported(edges{})); diff != "" {
+		t.Errorf("diff after removing vertex u a second time:\n%s", diff)
+	}
+	d.removeVertex(w)
+	want = dag{
+		v: edges{
+			in:  drawerSet{},
+			out: drawerSet{},
+		},
+	}
+	if diff := cmp.Diff(d, want, cmp.AllowUnexported(edges{})); diff != "" {
+		t.Errorf("diff after removing vertex v:\n%s", diff)
+	}
+}
+
+func TestTopWalk(t *testing.T) {
+	u := fakeDrawBoxer("u")
+	v := fakeDrawBoxer("v")
+	w := fakeDrawBoxer("w")
+	d := dag{
+		u: edges{
+			in:  drawerSet{},
+			out: drawerSet{v: {}},
+		},
+		v: edges{
+			in:  drawerSet{u: {}},
+			out: drawerSet{w: {}},
+		},
+		w: edges{
+			in:  drawerSet{v: {}},
+			out: drawerSet{},
+		},
+	}
+
+	var got []Drawer
+	d.topWalk(func(x Drawer) {
+		got = append(got, x)
+	})
+	want := []Drawer{u, v, w}
+	if diff := cmp.Diff(got, want); diff != "" {
+		t.Errorf("topWalk visited in wrong order - diff:\n%s", diff)
+	}
+}
+
+func TestTopWalkToleratesCycle(t *testing.T) {
+	u := fakeDrawBoxer("u")
+	v := fakeDrawBoxer("v")
+	w := fakeDrawBoxer("w")
+	d := dag{
+		u: edges{
+			in:  drawerSet{w: {}},
+			out: drawerSet{v: {}},
+		},
+		v: edges{
+			in:  drawerSet{u: {}},
+			out: drawerSet{w: {}},
+		},
+		w: edges{
+			in:  drawerSet{v: {}},
+			out: drawerSet{u: {}},
+		},
+	}
+	got := make(map[Drawer]int)
+	d.topWalk(func(x Drawer) {
+		got[x]++
+	})
+	want := map[Drawer]int{u: 1, v: 1, w: 1}
+	if diff := cmp.Diff(got, want); diff != "" {
+		t.Errorf("topWalk visited vertices wrong number of times - diff:\n%s", diff)
+	}
+}