rpc: Diff implementation

rpc/resource_provider.go

@@ -13,9 +13,28 @@ type ResourceProvider struct {
 	Name   string
 }
 
-func (p *ResourceProvider) Configure(c map[string]interface{}) ([]string, error) {
+func (p *ResourceProvider) Configure(c map[string]interface{}) error {
 	var resp ResourceProviderConfigureResponse
 	err := p.Client.Call(p.Name+".Configure", c, &resp)
+	if err != nil {
+		return err
+	}
+	if resp.Error != nil {
+		err = resp.Error
+	}
+
+	return err
+}
+
+func (p *ResourceProvider) Diff(
+	s *terraform.ResourceState,
+	c map[string]interface{}) (*terraform.ResourceDiff, error) {
+	var resp ResourceProviderDiffResponse
+	args := &ResourceProviderDiffArgs{
+		State:  s,
+		Config: c,
+	}
+	err := p.Client.Call(p.Name+".Diff", args, &resp)
 	if err != nil {
 		return nil, err
 	}
@@ -23,7 +42,7 @@ func (p *ResourceProvider) Configure(c map[string]interface{}) ([]string, error)
 		err = resp.Error
 	}
 
-	return resp.Warnings, err
+	return resp.Diff, err
 }
 
 func (p *ResourceProvider) Resources() []terraform.ResourceType {
@@ -45,16 +64,35 @@ type ResourceProviderServer struct {
 }
 
 type ResourceProviderConfigureResponse struct {
-	Warnings []string
+	Error *BasicError
+}
+
+type ResourceProviderDiffArgs struct {
+	State  *terraform.ResourceState
+	Config map[string]interface{}
+}
+
+type ResourceProviderDiffResponse struct {
+	Diff  *terraform.ResourceDiff
 	Error *BasicError
 }
 
 func (s *ResourceProviderServer) Configure(
 	config map[string]interface{},
 	reply *ResourceProviderConfigureResponse) error {
-	warnings, err := s.Provider.Configure(config)
+	err := s.Provider.Configure(config)
 	*reply = ResourceProviderConfigureResponse{
-		Warnings: warnings,
+		Error: NewBasicError(err),
+	}
+	return nil
+}
+
+func (s *ResourceProviderServer) Diff(
+	args *ResourceProviderDiffArgs,
+	result *ResourceProviderDiffResponse) error {
+	diff, err := s.Provider.Diff(args.State, args.Config)
+	*result = ResourceProviderDiffResponse{
+		Diff:  diff,
 		Error: NewBasicError(err),
 	}
 	return nil

rpc/resource_provider_test.go

@@ -19,16 +19,13 @@ func TestResourceProvider_configure(t *testing.T) {
 
 	// Configure
 	config := map[string]interface{}{"foo": "bar"}
-	w, e := provider.Configure(config)
+	e := provider.Configure(config)
 	if !p.ConfigureCalled {
 		t.Fatal("configure should be called")
 	}
 	if !reflect.DeepEqual(p.ConfigureConfig, config) {
 		t.Fatalf("bad: %#v", p.ConfigureConfig)
 	}
-	if w != nil {
-		t.Fatalf("bad: %#v", w)
-	}
 	if e != nil {
 		t.Fatalf("bad: %#v", e)
 	}
@@ -47,16 +44,13 @@ func TestResourceProvider_configure_errors(t *testing.T) {
 
 	// Configure
 	config := map[string]interface{}{"foo": "bar"}
-	w, e := provider.Configure(config)
+	e := provider.Configure(config)
 	if !p.ConfigureCalled {
 		t.Fatal("configure should be called")
 	}
 	if !reflect.DeepEqual(p.ConfigureConfig, config) {
 		t.Fatalf("bad: %#v", p.ConfigureConfig)
 	}
-	if w != nil {
-		t.Fatalf("bad: %#v", w)
-	}
 	if e == nil {
 		t.Fatal("should have error")
 	}
@@ -74,28 +68,85 @@ func TestResourceProvider_configure_warnings(t *testing.T) {
 	}
 	provider := &ResourceProvider{Client: client, Name: name}
 
-	p.ConfigureReturnWarnings = []string{"foo", "bar"}
-
 	// Configure
 	config := map[string]interface{}{"foo": "bar"}
-	w, e := provider.Configure(config)
+	e := provider.Configure(config)
 	if !p.ConfigureCalled {
 		t.Fatal("configure should be called")
 	}
 	if !reflect.DeepEqual(p.ConfigureConfig, config) {
 		t.Fatalf("bad: %#v", p.ConfigureConfig)
 	}
-	if w == nil {
-		t.Fatal("should have warnings")
-	}
-	if !reflect.DeepEqual(w, []string{"foo", "bar"}) {
-		t.Fatalf("bad: %#v", w)
-	}
 	if e != nil {
 		t.Fatalf("bad: %#v", e)
 	}
 }
 
+func TestResourceProvider_diff(t *testing.T) {
+	p := new(terraform.MockResourceProvider)
+	client, server := testClientServer(t)
+	name, err := Register(server, p)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	provider := &ResourceProvider{Client: client, Name: name}
+
+	p.DiffReturn = &terraform.ResourceDiff{
+		Attributes: map[string]*terraform.ResourceAttrDiff{
+			"foo": &terraform.ResourceAttrDiff{
+				Old: "",
+				New: "bar",
+			},
+		},
+	}
+
+	// Diff
+	state := &terraform.ResourceState{}
+	config := map[string]interface{}{"foo": "bar"}
+	diff, err := provider.Diff(state, config)
+	if !p.DiffCalled {
+		t.Fatal("diff should be called")
+	}
+	if !reflect.DeepEqual(p.DiffDesired, config) {
+		t.Fatalf("bad: %#v", p.DiffDesired)
+	}
+	if err != nil {
+		t.Fatalf("bad: %#v", err)
+	}
+	if !reflect.DeepEqual(p.DiffReturn, diff) {
+		t.Fatalf("bad: %#v", diff)
+	}
+}
+
+func TestResourceProvider_diff_error(t *testing.T) {
+	p := new(terraform.MockResourceProvider)
+	client, server := testClientServer(t)
+	name, err := Register(server, p)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	provider := &ResourceProvider{Client: client, Name: name}
+
+	p.DiffReturnError = errors.New("foo")
+
+	// Diff
+	state := &terraform.ResourceState{}
+	config := map[string]interface{}{"foo": "bar"}
+	diff, err := provider.Diff(state, config)
+	if !p.DiffCalled {
+		t.Fatal("diff should be called")
+	}
+	if !reflect.DeepEqual(p.DiffDesired, config) {
+		t.Fatalf("bad: %#v", p.DiffDesired)
+	}
+	if err == nil {
+		t.Fatal("should have error")
+	}
+	if diff != nil {
+		t.Fatal("should not have diff")
+	}
+}
+
 func TestResourceProvider_resources(t *testing.T) {
 	p := new(terraform.MockResourceProvider)
 	client, server := testClientServer(t)

terraform/resource_provider.go

@@ -30,7 +30,7 @@ type ResourceProvider interface {
 	// a diff.
 	Diff(
 		*ResourceState,
-		map[string]interface{}) (ResourceDiff, error)
+		map[string]interface{}) (*ResourceDiff, error)
 }
 
 // ResourceType is a type of resource that a resource provider can manage.

terraform/resource_provider_mock.go

@@ -12,8 +12,8 @@ type MockResourceProvider struct {
 	DiffCalled           bool
 	DiffState            *ResourceState
 	DiffDesired          map[string]interface{}
-	DiffFn               func(*ResourceState, map[string]interface{}) (ResourceDiff, error)
+	DiffFn               func(*ResourceState, map[string]interface{}) (*ResourceDiff, error)
-	DiffReturn           ResourceDiff
+	DiffReturn           *ResourceDiff
 	DiffReturnError      error
 	ResourcesCalled      bool
 	ResourcesReturn      []ResourceType
@@ -27,7 +27,7 @@ func (p *MockResourceProvider) Configure(c map[string]interface{}) error {
 
 func (p *MockResourceProvider) Diff(
 	state *ResourceState,
-	desired map[string]interface{}) (ResourceDiff, error) {
+	desired map[string]interface{}) (*ResourceDiff, error) {
 	p.DiffCalled = true
 	p.DiffState = state
 	p.DiffDesired = desired

terraform/terraform_test.go

@@ -261,7 +261,7 @@ func testProviderFunc(n string, rs []string) ResourceProviderFactory {
 	return func() (ResourceProvider, error) {
 		diffFn := func(
 			_ *ResourceState,
-			c map[string]interface{}) (ResourceDiff, error) {
+			c map[string]interface{}) (*ResourceDiff, error) {
 			var diff ResourceDiff
 			diff.Attributes = make(map[string]*ResourceAttrDiff)
 			for k, v := range c {
@@ -290,7 +290,7 @@ func testProviderFunc(n string, rs []string) ResourceProviderFactory {
 				diff.Attributes[k] = attrDiff
 			}
 
-			return diff, nil
+			return &diff, nil
 		}
 
 		result := &MockResourceProvider{