core: Update TestContext2Apply_multiVarComprehensive for new assumptions

This comprehensive test was covering a few different behaviors that are
intentionally different for v0.12:

- Applying the splat operator to a list of resource instances that haven't
  been created yet produces a list of unknown values rather than a single
  unknown list as before. This is important because it allows that list
  to be passed into length().

- Wrapping a splat expression in another round of brackets now produces
  a list of lists, whereas before we had a special case (for compatibility
  with prior to v0.10) that would flatten this away in the schema layer.

terraform/context_apply_test.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"github.com/davecgh/go-spew/spew"
+	"github.com/go-test/deep"
 	"github.com/zclconf/go-cty/cty"
 
 	"github.com/hashicorp/terraform/addrs"
@@ -3514,8 +3515,8 @@ func TestContext2Apply_multiVarComprehensive(t *testing.T) {
 					"source_names":           {Type: cty.List(cty.String), Optional: true},
 					"source_ids_from_func":   {Type: cty.List(cty.String), Optional: true},
 					"source_names_from_func": {Type: cty.List(cty.String), Optional: true},
-					"source_ids_wrapped":     {Type: cty.List(cty.String), Optional: true},
-					"source_names_wrapped":   {Type: cty.List(cty.String), Optional: true},
+					"source_ids_wrapped":     {Type: cty.List(cty.List(cty.String)), Optional: true},
+					"source_names_wrapped":   {Type: cty.List(cty.List(cty.String)), Optional: true},
 
 					"id":   {Type: cty.String, Computed: true},
 					"name": {Type: cty.String, Computed: true},
@@ -3546,32 +3547,45 @@ func TestContext2Apply_multiVarComprehensive(t *testing.T) {
 
 	checkConfig := func(name string, want map[string]interface{}) {
 		got := configs[name].Config
-		if !reflect.DeepEqual(got, want) {
-			t.Errorf(
-				"wrong config for %s\ngot:  %s\nwant: %s",
-				name, spew.Sdump(got), spew.Sdump(want),
-			)
-		}
+		t.Run("config for "+name, func(t *testing.T) {
+			for _, problem := range deep.Equal(got, want) {
+				t.Errorf(problem)
+			}
+		})
 	}
 
 	checkConfig("test_thing.multi_count_var.0", map[string]interface{}{
+		"id":          unknownValue(),
+		"name":        unknownValue(),
 		"source_id":   unknownValue(),
 		"source_name": "test_thing.source.0",
 	})
 	checkConfig("test_thing.multi_count_var.2", map[string]interface{}{
+		"id":          unknownValue(),
+		"name":        unknownValue(),
 		"source_id":   unknownValue(),
 		"source_name": "test_thing.source.2",
 	})
 	checkConfig("test_thing.multi_count_derived.0", map[string]interface{}{
+		"id":          unknownValue(),
+		"name":        unknownValue(),
 		"source_id":   unknownValue(),
 		"source_name": "test_thing.source.0",
 	})
 	checkConfig("test_thing.multi_count_derived.2", map[string]interface{}{
+		"id":          unknownValue(),
+		"name":        unknownValue(),
 		"source_id":   unknownValue(),
 		"source_name": "test_thing.source.2",
 	})
 	checkConfig("test_thing.whole_splat", map[string]interface{}{
-		"source_ids": unknownValue(),
+		"id":   unknownValue(),
+		"name": unknownValue(),
+		"source_ids": []interface{}{
+			unknownValue(),
+			unknownValue(),
+			unknownValue(),
+		},
 		"source_names": []interface{}{
 			"test_thing.source.0",
 			"test_thing.source.1",
@@ -3584,47 +3598,60 @@ func TestContext2Apply_multiVarComprehensive(t *testing.T) {
 			"test_thing.source.2",
 		},
 
-		// This one ends up being a list with a single unknown value at this
-		// layer, but is fixed up inside helper/schema. There is a test for
-		// this inside the "test" provider, since core tests can't exercise
-		// helper/schema functionality.
-		"source_ids_wrapped": []interface{}{unknownValue()},
-
-		"source_names_wrapped": []interface{}{
-			"test_thing.source.0",
-			"test_thing.source.1",
-			"test_thing.source.2",
+		"source_ids_wrapped": []interface{}{
+			[]interface{}{
+				unknownValue(),
+				unknownValue(),
+				unknownValue(),
+			},
 		},
+		"source_names_wrapped": []interface{}{
+			[]interface{}{
+				"test_thing.source.0",
+				"test_thing.source.1",
+				"test_thing.source.2",
+			},
+		},
+
 		"first_source_id":   unknownValue(),
 		"first_source_name": "test_thing.source.0",
 	})
 	checkConfig("module.child.test_thing.whole_splat", map[string]interface{}{
-		"source_ids": unknownValue(),
+		"id":   unknownValue(),
+		"name": unknownValue(),
+		"source_ids": []interface{}{
+			unknownValue(),
+			unknownValue(),
+			unknownValue(),
+		},
 		"source_names": []interface{}{
 			"test_thing.source.0",
 			"test_thing.source.1",
 			"test_thing.source.2",
 		},
 
-		// This one ends up being a list with a single unknown value at this
-		// layer, but is fixed up inside helper/schema. There is a test for
-		// this inside the "test" provider, since core tests can't exercise
-		// helper/schema functionality.
-		"source_ids_wrapped": []interface{}{unknownValue()},
-
+		"source_ids_wrapped": []interface{}{
+			[]interface{}{
+				unknownValue(),
+				unknownValue(),
+				unknownValue(),
+			},
+		},
 		"source_names_wrapped": []interface{}{
-			"test_thing.source.0",
-			"test_thing.source.1",
-			"test_thing.source.2",
+			[]interface{}{
+				"test_thing.source.0",
+				"test_thing.source.1",
+				"test_thing.source.2",
+			},
 		},
 	})
 
-	state, diags := ctx.Apply()
-	if diags.HasErrors() {
-		t.Fatalf("error during apply: %s", diags.Err())
-	}
+	t.Run("apply", func(t *testing.T) {
+		state, diags := ctx.Apply()
+		if diags.HasErrors() {
+			t.Fatalf("error during apply: %s", diags.Err())
+		}
 
-	{
 		want := map[string]interface{}{
 			"source_ids": []interface{}{"foo", "foo", "foo"},
 			"source_names": []interface{}{
@@ -3643,7 +3670,7 @@ func TestContext2Apply_multiVarComprehensive(t *testing.T) {
 				spew.Sdump(got), spew.Sdump(want),
 			)
 		}
-	}
+	})
 }
 
 // Test that multi-var (splat) access is ordered by count, not by

terraform/test-fixtures/apply-multi-var-comprehensive/child/child.tf

@@ -10,16 +10,16 @@ variable "source_names" {
 }
 
 resource "test_thing" "multi_count_var" {
-  count = "${var.num}"
+  count = var.num
 
   # Can pluck a single item out of a multi-var
-  source_id = "${var.source_ids[count.index]}"
+  source_id = var.source_ids[count.index]
 }
 
 resource "test_thing" "whole_splat" {
   # Can "splat" the ids directly into an attribute of type list.
-  source_ids = "${var.source_ids}"
-  source_names = "${var.source_names}"
-  source_ids_wrapped = ["${var.source_ids}"]
+  source_ids           = var.source_ids
+  source_names         = var.source_names
+  source_ids_wrapped   = ["${var.source_ids}"]
   source_names_wrapped = ["${var.source_names}"]
 }

terraform/test-fixtures/apply-multi-var-comprehensive/root.tf

@@ -2,48 +2,48 @@ variable "num" {
 }
 
 resource "test_thing" "source" {
-  count = "${var.num}"
+  count = var.num
 
   # The diffFunc in the test exports "name" here too, which we can use
   # to test values that are known during plan.
 }
 
 resource "test_thing" "multi_count_var" {
-  count = "${var.num}"
+  count = var.num
 
   # Can pluck a single item out of a multi-var
-  source_id   = "${test_thing.source.*.id[count.index]}"
-  source_name = "${test_thing.source.*.name[count.index]}"
+  source_id   = test_thing.source.*.id[count.index]
+  source_name = test_thing.source.*.name[count.index]
 }
 
 resource "test_thing" "multi_count_derived" {
   # Can use the source to get the count
-  count = "${length(test_thing.source)}"
+  count = length(test_thing.source)
 
-  source_id   = "${test_thing.source.*.id[count.index]}"
-  source_name = "${test_thing.source.*.name[count.index]}"
+  source_id   = test_thing.source.*.id[count.index]
+  source_name = test_thing.source.*.name[count.index]
 }
 
 resource "test_thing" "whole_splat" {
   # Can "splat" the ids directly into an attribute of type list.
-  source_ids   = "${test_thing.source.*.id}"
-  source_names = "${test_thing.source.*.name}"
+  source_ids   = test_thing.source.*.id
+  source_names = test_thing.source.*.name
 
   # Accessing through a function should work.
-  source_ids_from_func   = "${split(" ", join(" ", test_thing.source.*.id))}"
-  source_names_from_func = "${split(" ", join(" ", test_thing.source.*.name))}"
+  source_ids_from_func   = split(" ", join(" ", test_thing.source.*.id))
+  source_names_from_func = split(" ", join(" ", test_thing.source.*.name))
 
   # A common pattern of selecting with a default.
-  first_source_id   = "${element(concat(test_thing.source.*.id, list("default")), 0)}"
-  first_source_name = "${element(concat(test_thing.source.*.name, list("default")), 0)}"
+  first_source_id   = element(concat(test_thing.source.*.id, ["default"]), 0)
+  first_source_name = element(concat(test_thing.source.*.name, ["default"]), 0)
 
-  # Legacy form: Prior to Terraform having comprehensive list support,
-  # splats were treated as a special case and required to be presented
-  # in a wrapping list. This is no longer the suggested form, but we
-  # need it to keep working for compatibility.
-  #
-  # This should result in exactly the same result as the above, even
-  # though it looks like it would result in a list of lists.
+  # Prior to v0.12 we were handling lists containing list interpolations as
+  # a special case, flattening the result, for compatibility with behavior
+  # prior to v0.10. This deprecated handling is now removed, and so these
+  # each produce a list of lists. We're still using the interpolation syntax
+  # here, rather than the splat expression directly, to properly mimic how
+  # this would've looked prior to v0.12 to be explicit about what the new
+  # behavior is for this old syntax.
   source_ids_wrapped   = ["${test_thing.source.*.id}"]
   source_names_wrapped = ["${test_thing.source.*.name}"]
 
@@ -52,15 +52,15 @@ resource "test_thing" "whole_splat" {
 module "child" {
   source = "./child"
 
-  num          = "${var.num}"
-  source_ids   = "${test_thing.source.*.id}"
-  source_names = "${test_thing.source.*.name}"
+  num          = var.num
+  source_ids   = test_thing.source.*.id
+  source_names = test_thing.source.*.name
 }
 
 output "source_ids" {
-  value = "${test_thing.source.*.id}"
+  value = test_thing.source.*.id
 }
 
 output "source_names" {
-  value = "${test_thing.source.*.name}"
+  value = test_thing.source.*.name
 }