terraform: test count = 1 variable access

terraform/context.go

@@ -1498,10 +1498,15 @@ func (c *walkContext) computeResourceVariable(
 
 	r, ok := module.Resources[id]
 	if !ok {
-		return "", fmt.Errorf(
+		if v.Multi && v.Index == 0 {
-			"Resource '%s' not found for variable '%s'",
+			r, ok = module.Resources[v.ResourceId()]
-			id,
+		}
-			v.FullKey())
+		if !ok {
+			return "", fmt.Errorf(
+				"Resource '%s' not found for variable '%s'",
+				id,
+				v.FullKey())
+		}
 	}
 
 	if r.Primary == nil {

terraform/context_test.go

@@ -2513,6 +2513,29 @@ func TestContextPlan_countZero(t *testing.T) {
 	}
 }
 
+func TestContextPlan_countOneIndex(t *testing.T) {
+	m := testModule(t, "plan-count-one-index")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	plan, err := ctx.Plan(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(plan.String())
+	expected := strings.TrimSpace(testTerraformPlanCountOneIndexStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func TestContextPlan_countDecreaseToOne(t *testing.T) {
 	m := testModule(t, "plan-count-dec")
 	p := testProvider("aws")

terraform/terraform_test.go

@@ -477,6 +477,21 @@ STATE:
 <no state>
 `
 
+const testTerraformPlanCountOneIndexStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo
+  foo:  "" => "foo"
+  type: "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+
 const testTerraformPlanCountZeroStr = `
 DIFF:
 

terraform/test-fixtures/plan-count-one-index/main.tf

@@ -0,0 +1,8 @@
+resource "aws_instance" "foo" {
+    count = 1
+    foo = "foo"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.0.foo}"
+}