test for CBD instance being removed entirely

Even though this is only the destroy half of CreateBeforeDestroy, the
resource may still require the same destroy order.

terraform/graph_builder_apply_test.go

@@ -610,6 +610,111 @@ test_object.b
 	}
 }
 
+// Ensure that an update resulting from the removal of a resource happens before
+// a CBD resource is destroyed.
+func TestApplyGraphBuilder_updateFromCBDOrphan(t *testing.T) {
+	schemas := simpleTestSchemas()
+	instanceSchema := schemas.Providers[addrs.NewLegacyProvider("test")].ResourceTypes["test_object"]
+
+	bBefore, _ := plans.NewDynamicValue(
+		cty.ObjectVal(map[string]cty.Value{
+			"id":          cty.StringVal("b_id"),
+			"test_string": cty.StringVal("a_id"),
+		}), instanceSchema.ImpliedType())
+	bAfter, _ := plans.NewDynamicValue(
+		cty.ObjectVal(map[string]cty.Value{
+			"id":          cty.StringVal("b_id"),
+			"test_string": cty.StringVal("changed"),
+		}), instanceSchema.ImpliedType())
+
+	changes := &plans.Changes{
+		Resources: []*plans.ResourceInstanceChangeSrc{
+			{
+				Addr: mustResourceInstanceAddr("test_object.a"),
+				ChangeSrc: plans.ChangeSrc{
+					Action: plans.Delete,
+				},
+			},
+			{
+				Addr: mustResourceInstanceAddr("test_object.b"),
+				ChangeSrc: plans.ChangeSrc{
+					Action: plans.Update,
+					Before: bBefore,
+					After:  bAfter,
+				},
+			},
+		},
+	}
+
+	state := states.NewState()
+	root := state.EnsureModule(addrs.RootModuleInstance)
+	root.SetResourceInstanceCurrent(
+		addrs.Resource{
+			Mode: addrs.ManagedResourceMode,
+			Type: "test_object",
+			Name: "a",
+		}.Instance(addrs.NoKey),
+		&states.ResourceInstanceObjectSrc{
+			Status:              states.ObjectReady,
+			AttrsJSON:           []byte(`{"id":"a_id"}`),
+			CreateBeforeDestroy: true,
+		},
+		addrs.LocalProviderConfig{
+			LocalName: "test",
+		}.Absolute(addrs.RootModuleInstance),
+	)
+	root.SetResourceInstanceCurrent(
+		addrs.Resource{
+			Mode: addrs.ManagedResourceMode,
+			Type: "test_object",
+			Name: "b",
+		}.Instance(addrs.NoKey),
+		&states.ResourceInstanceObjectSrc{
+			Status:    states.ObjectReady,
+			AttrsJSON: []byte(`{"id":"b_id","test_string":"a_id"}`),
+			Dependencies: []addrs.AbsResource{
+				addrs.AbsResource{
+					Resource: addrs.Resource{
+						Mode: addrs.ManagedResourceMode,
+						Type: "test_object",
+						Name: "a",
+					},
+					Module: root.Addr,
+				},
+			},
+		},
+		addrs.LocalProviderConfig{
+			LocalName: "test",
+		}.Absolute(addrs.RootModuleInstance),
+	)
+
+	b := &ApplyGraphBuilder{
+		Config:     testModule(t, "graph-builder-apply-orphan-update"),
+		Changes:    changes,
+		Components: simpleMockComponentFactory(),
+		Schemas:    schemas,
+		State:      state,
+	}
+
+	g, err := b.Build(addrs.RootModuleInstance)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	expected := strings.TrimSpace(`
+test_object.a (destroy)
+  test_object.b
+test_object.b
+`)
+
+	instanceGraph := filterInstances(g)
+	got := strings.TrimSpace(instanceGraph.String())
+
+	if got != expected {
+		t.Fatalf("expected:\n%s\ngot:\n%s", expected, got)
+	}
+}
+
 // The orphan clean up node should not be connected to a provider
 func TestApplyGraphBuilder_orphanedWithProvider(t *testing.T) {
 	changes := &plans.Changes{