terraform: shadow resource provider Apply

terraform/shadow_resource_provider.go

@@ -108,6 +108,21 @@ func (p *shadowResourceProviderReal) Configure(c *ResourceConfig) error {
 	return err
 }
 
+func (p *shadowResourceProviderReal) Apply(
+	info *InstanceInfo,
+	state *InstanceState,
+	diff *InstanceDiff) (*InstanceState, error) {
+	result, err := p.ResourceProvider.Apply(info, state, diff)
+	p.Shared.Apply.SetValue(info.HumanId(), &shadowResourceProviderApply{
+		State:     state,
+		Diff:      diff,
+		Result:    result,
+		ResultErr: err,
+	})
+
+	return result, err
+}
+
 // shadowResourceProviderShadow is the shadow resource provider. Function
 // calls never affect real resources. This is paired with the "real" side
 // which must be called properly to enable recording.
@@ -127,6 +142,7 @@ type shadowResourceProviderShared struct {
 	Input     shadow.Value
 	Validate  shadow.Value
 	Configure shadow.Value
+	Apply     shadow.KeyedValue
 }
 
 func (p *shadowResourceProviderShadow) CloseShadow() error {
@@ -241,6 +257,45 @@ func (p *shadowResourceProviderShadow) Configure(c *ResourceConfig) error {
 	return result.Result
 }
 
+func (p *shadowResourceProviderShadow) Apply(
+	info *InstanceInfo,
+	state *InstanceState,
+	diff *InstanceDiff) (*InstanceState, error) {
+	// Unique key
+	key := info.HumanId()
+	raw := p.Shared.Apply.Value(key)
+	if raw == nil {
+		p.ErrorLock.Lock()
+		defer p.ErrorLock.Unlock()
+		p.Error = multierror.Append(p.Error, fmt.Errorf(
+			"Unknown 'apply' call for %q:\n\n%#v\n\n%#v",
+			key, state, diff))
+		return nil, nil
+	}
+
+	result, ok := raw.(*shadowResourceProviderApply)
+	if !ok {
+		p.ErrorLock.Lock()
+		defer p.ErrorLock.Unlock()
+		p.Error = multierror.Append(p.Error, fmt.Errorf(
+			"Unknown 'apply' shadow value: %#v", raw))
+		return nil, nil
+	}
+
+	// Compare the parameters, which should be identical
+	if !state.Equal(result.State) {
+		p.ErrorLock.Lock()
+		p.Error = multierror.Append(p.Error, fmt.Errorf(
+			"State had unequal states (real, then shadow):\n\n%#v\n\n%#v",
+			result.State, state))
+		p.ErrorLock.Unlock()
+	}
+
+	// TODO: compare diffs
+
+	return result.Result, result.ResultErr
+}
+
 // TODO
 // TODO
 // TODO
@@ -251,13 +306,6 @@ func (p *shadowResourceProviderShadow) ValidateResource(t string, c *ResourceCon
 	return nil, nil
 }
 
-func (p *shadowResourceProviderShadow) Apply(
-	info *InstanceInfo,
-	state *InstanceState,
-	diff *InstanceDiff) (*InstanceState, error) {
-	return nil, nil
-}
-
 func (p *shadowResourceProviderShadow) Diff(
 	info *InstanceInfo,
 	state *InstanceState,
@@ -310,3 +358,10 @@ type shadowResourceProviderConfigure struct {
 	Config *ResourceConfig
 	Result error
 }
+
+type shadowResourceProviderApply struct {
+	State     *InstanceState
+	Diff      *InstanceDiff
+	Result    *InstanceState
+	ResultErr error
+}

terraform/shadow_resource_provider_test.go

@@ -265,3 +265,57 @@ func TestShadowResourceProviderConfigure_badInput(t *testing.T) {
 		t.Fatal("should have error")
 	}
 }
+
+func TestShadowResourceProviderApply(t *testing.T) {
+	mock := new(MockResourceProvider)
+	real, shadow := newShadowResourceProvider(mock)
+
+	// Test values
+	info := &InstanceInfo{Id: "foo"}
+	state := &InstanceState{ID: "foo"}
+	diff := &InstanceDiff{Destroy: true}
+	mockResult := &InstanceState{ID: "bar"}
+
+	// Configure the mock
+	mock.ApplyReturn = mockResult
+
+	// Verify that it blocks until the real func is called
+	var result *InstanceState
+	var err error
+	doneCh := make(chan struct{})
+	go func() {
+		defer close(doneCh)
+		result, err = shadow.Apply(info, state, diff)
+	}()
+
+	select {
+	case <-doneCh:
+		t.Fatal("should block until finished")
+	case <-time.After(10 * time.Millisecond):
+	}
+
+	// Call the real func
+	realResult, realErr := real.Apply(info, state, diff)
+	if !realResult.Equal(mockResult) {
+		t.Fatalf("bad: %#v", realResult)
+	}
+	if realErr != nil {
+		t.Fatalf("bad: %#v", realErr)
+	}
+
+	// The shadow should finish now
+	<-doneCh
+
+	// Verify the shadow returned the same values
+	if !result.Equal(mockResult) {
+		t.Fatalf("bad: %#v", result)
+	}
+	if err != nil {
+		t.Fatalf("bad: %#v", err)
+	}
+
+	// Verify we have no errors
+	if err := shadow.CloseShadow(); err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+}