diff --git a/command/apply_test.go b/command/apply_test.go
index 74719c32a0..280568b4f0 100644
--- a/command/apply_test.go
+++ b/command/apply_test.go
@@ -341,43 +341,26 @@ func TestApply_error(t *testing.T) {
 
 	var lock sync.Mutex
 	errored := false
-	p.ApplyFn = func(info *terraform.InstanceInfo, s *terraform.InstanceState, d *terraform.InstanceDiff) (*terraform.InstanceState, error) {
+	p.ApplyResourceChangeFn = func(req providers.ApplyResourceChangeRequest) (resp providers.ApplyResourceChangeResponse) {
 		lock.Lock()
 		defer lock.Unlock()
 
 		if !errored {
 			errored = true
-			return nil, fmt.Errorf("error")
+			resp.Diagnostics = resp.Diagnostics.Append(fmt.Errorf("error"))
 		}
 
-		newState := &terraform.InstanceState{
-			ID:         "foo",
-			Attributes: map[string]string{},
-		}
-		newState.Attributes["id"] = newState.ID
-		if ad, ok := d.Attributes["ami"]; ok {
-			newState.Attributes["ami"] = ad.New
-		}
-		if ad, ok := d.Attributes["error"]; ok {
-			newState.Attributes["error"] = ad.New
-		}
-		return newState, nil
+		s := req.PlannedState.AsValueMap()
+		s["id"] = cty.StringVal("foo")
+
+		resp.NewState = cty.ObjectVal(s)
+		return
 	}
-	p.DiffFn = func(info *terraform.InstanceInfo, s *terraform.InstanceState, rc *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
-		ret := &terraform.InstanceDiff{
-			Attributes: map[string]*terraform.ResourceAttrDiff{},
-		}
-		if new, ok := rc.Get("ami"); ok {
-			ret.Attributes["ami"] = &terraform.ResourceAttrDiff{
-				New: new.(string),
-			}
-		}
-		if new, ok := rc.Get("error"); ok {
-			ret.Attributes["error"] = &terraform.ResourceAttrDiff{
-				New: fmt.Sprintf("%t", new.(bool)),
-			}
-		}
-		return ret, nil
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
+		s := req.ProposedNewState.AsValueMap()
+		s["id"] = cty.UnknownVal(cty.String)
+		resp.PlannedState = cty.ObjectVal(s)
+		return
 	}
 	p.GetSchemaReturn = &terraform.ProviderSchema{
 		ResourceTypes: map[string]*configschema.Block{
@@ -902,25 +885,13 @@ func TestApply_shutdown(t *testing.T) {
 		return nil
 	}
 
-	p.DiffFn = func(
-		*terraform.InstanceInfo,
-		*terraform.InstanceState,
-		*terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
-		return &terraform.InstanceDiff{
-			Attributes: map[string]*terraform.ResourceAttrDiff{
-				"ami": &terraform.ResourceAttrDiff{
-					New: "bar",
-				},
-			},
-		}, nil
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
+		resp.PlannedState = req.ProposedNewState
+		return
 	}
 
 	var once sync.Once
-	p.ApplyFn = func(
-		*terraform.InstanceInfo,
-		*terraform.InstanceState,
-		*terraform.InstanceDiff) (*terraform.InstanceState, error) {
-
+	p.ApplyResourceChangeFn = func(req providers.ApplyResourceChangeRequest) (resp providers.ApplyResourceChangeResponse) {
 		// only cancel once
 		once.Do(func() {
 			shutdownCh <- struct{}{}
@@ -934,12 +905,8 @@ func TestApply_shutdown(t *testing.T) {
 		// canceled.
 		time.Sleep(200 * time.Millisecond)
 
-		return &terraform.InstanceState{
-			ID: "foo",
-			Attributes: map[string]string{
-				"ami": "2",
-			},
-		}, nil
+		resp.NewState = req.PlannedState
+		return
 	}
 
 	p.GetSchemaReturn = &terraform.ProviderSchema{
diff --git a/command/import_test.go b/command/import_test.go
index 21174727c1..bde634c214 100644
--- a/command/import_test.go
+++ b/command/import_test.go
@@ -110,7 +110,7 @@ func TestImport_providerConfig(t *testing.T) {
 	}
 
 	configured := false
-	p.ConfigureNewFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
+	p.ConfigureFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
 		configured = true
 
 		cfg := req.Config
@@ -217,7 +217,7 @@ func TestImport_remoteState(t *testing.T) {
 	}
 
 	configured := false
-	p.ConfigureNewFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
+	p.ConfigureFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
 		var diags tfdiags.Diagnostics
 		configured = true
 		if got, want := req.Config.GetAttr("foo"), cty.StringVal("bar"); !want.RawEquals(got) {
@@ -364,7 +364,7 @@ func TestImport_providerConfigWithVar(t *testing.T) {
 	}
 
 	configured := false
-	p.ConfigureNewFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
+	p.ConfigureFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
 		var diags tfdiags.Diagnostics
 		configured = true
 		if got, want := req.Config.GetAttr("foo"), cty.StringVal("bar"); !want.RawEquals(got) {
@@ -495,7 +495,7 @@ func TestImport_providerConfigWithVarDefault(t *testing.T) {
 	}
 
 	configured := false
-	p.ConfigureNewFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
+	p.ConfigureFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
 		var diags tfdiags.Diagnostics
 		configured = true
 		if got, want := req.Config.GetAttr("foo"), cty.StringVal("bar"); !want.RawEquals(got) {
@@ -568,7 +568,7 @@ func TestImport_providerConfigWithVarFile(t *testing.T) {
 	}
 
 	configured := false
-	p.ConfigureNewFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
+	p.ConfigureFn = func(req providers.ConfigureRequest) providers.ConfigureResponse {
 		var diags tfdiags.Diagnostics
 		configured = true
 		if got, want := req.Config.GetAttr("foo"), cty.StringVal("bar"); !want.RawEquals(got) {
diff --git a/command/plan_test.go b/command/plan_test.go
index 46b631a6f0..831f45dfc0 100644
--- a/command/plan_test.go
+++ b/command/plan_test.go
@@ -524,15 +524,10 @@ func TestPlan_vars(t *testing.T) {
 	}
 
 	actual := ""
-	p.DiffFn = func(
-		info *terraform.InstanceInfo,
-		s *terraform.InstanceState,
-		c *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
-		if v, ok := c.Config["value"]; ok {
-			actual = v.(string)
-		}
-
-		return nil, nil
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
+		actual = req.ProposedNewState.GetAttr("value").AsString()
+		resp.PlannedState = req.ProposedNewState
+		return
 	}
 
 	args := []string{
@@ -656,15 +651,10 @@ func TestPlan_varFile(t *testing.T) {
 	}
 
 	actual := ""
-	p.DiffFn = func(
-		info *terraform.InstanceInfo,
-		s *terraform.InstanceState,
-		c *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
-		if v, ok := c.Config["value"]; ok {
-			actual = v.(string)
-		}
-
-		return nil, nil
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
+		actual = req.ProposedNewState.GetAttr("value").AsString()
+		resp.PlannedState = req.ProposedNewState
+		return
 	}
 
 	args := []string{
@@ -706,15 +696,10 @@ func TestPlan_varFileDefault(t *testing.T) {
 	}
 
 	actual := ""
-	p.DiffFn = func(
-		info *terraform.InstanceInfo,
-		s *terraform.InstanceState,
-		c *terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
-		if v, ok := c.Config["value"]; ok {
-			actual = v.(string)
-		}
-
-		return nil, nil
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
+		actual = req.ProposedNewState.GetAttr("value").AsString()
+		resp.PlannedState = req.ProposedNewState
+		return
 	}
 
 	args := []string{
@@ -824,11 +809,7 @@ func TestPlan_shutdown(t *testing.T) {
 
 	var once sync.Once
 
-	p.DiffFn = func(
-		*terraform.InstanceInfo,
-		*terraform.InstanceState,
-		*terraform.ResourceConfig) (*terraform.InstanceDiff, error) {
-
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
 		once.Do(func() {
 			shutdownCh <- struct{}{}
 		})
@@ -841,14 +822,12 @@ func TestPlan_shutdown(t *testing.T) {
 		// canceled.
 		time.Sleep(200 * time.Millisecond)
 
-		return &terraform.InstanceDiff{
-			Attributes: map[string]*terraform.ResourceAttrDiff{
-				"ami": &terraform.ResourceAttrDiff{
-					New: "bar",
-				},
-			},
-		}, nil
+		s := req.ProposedNewState.AsValueMap()
+		s["ami"] = cty.StringVal("bar")
+		resp.PlannedState = cty.ObjectVal(s)
+		return
 	}
+
 	p.GetSchemaReturn = &terraform.ProviderSchema{
 		ResourceTypes: map[string]*configschema.Block{
 			"test_instance": {