core: Add resource count scale-out EvalTree test

This test ensures that the right EvalSequence gets set for a refresh
node with no state. This will ultimately assert that nodes on scale out
will not go down the regular refresh path, which would result in an
error due to the nil state - instead, we stub this node so that we get a
diff on it that can be used to effect computed/unknown values on
interpolations that may depend on this node.

terraform/node_resource_refresh_test.go

@@ -1,8 +1,11 @@
 package terraform
 
 import (
+	"reflect"
 	"sync"
 	"testing"
+
+	"github.com/davecgh/go-spew/spew"
 )
 
 func TestNodeRefreshableManagedResourceDynamicExpand_scaleOut(t *testing.T) {
@@ -152,3 +155,80 @@ root - terraform.graphNodeRoot
 		t.Fatalf("Expected:\n%s\nGot:\n%s", expected, actual)
 	}
 }
+
+func TestNodeRefreshableManagedResourceEvalTree_scaleOut(t *testing.T) {
+	var provider ResourceProvider
+	var state *InstanceState
+	var resourceConfig *ResourceConfig
+
+	addr, err := ParseResourceAddress("aws_instance.foo[2]")
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+
+	m := testModule(t, "refresh-resource-scale-inout")
+
+	n := &NodeRefreshableManagedResourceInstance{
+		NodeAbstractResource: &NodeAbstractResource{
+			Addr:   addr,
+			Config: m.Config().Resources[0],
+		},
+	}
+
+	actual := n.EvalTree()
+
+	expected := &EvalSequence{
+		Nodes: []EvalNode{
+			&EvalInterpolate{
+				Config: n.Config.RawConfig.Copy(),
+				Resource: &Resource{
+					Name:       addr.Name,
+					Type:       addr.Type,
+					CountIndex: addr.Index,
+				},
+				Output: &resourceConfig,
+			},
+			&EvalGetProvider{
+				Name:   n.ProvidedBy()[0],
+				Output: &provider,
+			},
+			&EvalValidateResource{
+				Provider:       &provider,
+				Config:         &resourceConfig,
+				ResourceName:   n.Config.Name,
+				ResourceType:   n.Config.Type,
+				ResourceMode:   n.Config.Mode,
+				IgnoreWarnings: true,
+			},
+			&EvalReadState{
+				Name:   addr.stateId(),
+				Output: &state,
+			},
+			&EvalDiff{
+				Name: addr.stateId(),
+				Info: &InstanceInfo{
+					Id:         addr.stateId(),
+					Type:       addr.Type,
+					ModulePath: normalizeModulePath(addr.Path),
+				},
+				Config:      &resourceConfig,
+				Resource:    n.Config,
+				Provider:    &provider,
+				State:       &state,
+				OutputState: &state,
+				Stub:        true,
+			},
+			&EvalWriteState{
+				Name:         addr.stateId(),
+				ResourceType: n.Config.Type,
+				Provider:     n.Config.Provider,
+				Dependencies: n.StateReferences(),
+				State:        &state,
+			},
+		},
+	}
+
+	if !reflect.DeepEqual(expected, actual) {
+		t.Fatalf("Expected:\n\n%s\nGot:\n\n%s\n", spew.Sdump(expected), spew.Sdump(actual))
+	}
+}