insert empty objects into config from empty blocks

When creating a legacy config from a cty.Value, empty nested blocks
should corespond to empty objects in the config.

config/hcl2shim/values.go

@@ -80,11 +80,6 @@ func ConfigValueFromHCL2Block(v cty.Value, schema *configschema.Block) map[strin
 
 		case configschema.NestingList, configschema.NestingSet:
 			l := bv.LengthInt()
-			if l == 0 {
-				// skip empty collections to better mimic how HCL1 would behave
-				continue
-			}
-
 			elems := make([]interface{}, 0, l)
 			for it := bv.ElementIterator(); it.Next(); {
 				_, ev := it.Element()
@@ -97,11 +92,6 @@ func ConfigValueFromHCL2Block(v cty.Value, schema *configschema.Block) map[strin
 			ret[name] = elems
 
 		case configschema.NestingMap:
-			if bv.LengthInt() == 0 {
-				// skip empty collections to better mimic how HCL1 would behave
-				continue
-			}
-
 			elems := make(map[string]interface{})
 			for it := bv.ElementIterator(); it.Next(); {
 				ek, ev := it.Element()

config/hcl2shim/values_test.go

@@ -151,7 +151,7 @@ func TestConfigValueFromHCL2Block(t *testing.T) {
 		},
 		{
 			cty.ObjectVal(map[string]cty.Value{
-				"address": cty.ListValEmpty(cty.EmptyObject), // should be omitted altogether in result
+				"address": cty.ListValEmpty(cty.EmptyObject),
 			}),
 			&configschema.Block{
 				BlockTypes: map[string]*configschema.NestedBlock{
@@ -161,7 +161,9 @@ func TestConfigValueFromHCL2Block(t *testing.T) {
 					},
 				},
 			},
-			map[string]interface{}{},
+			map[string]interface{}{
+				"address": []interface{}{},
+			},
 		},
 		{
 			cty.ObjectVal(map[string]cty.Value{
@@ -193,7 +195,9 @@ func TestConfigValueFromHCL2Block(t *testing.T) {
 					},
 				},
 			},
-			map[string]interface{}{},
+			map[string]interface{}{
+				"address": []interface{}{},
+			},
 		},
 		{
 			cty.ObjectVal(map[string]cty.Value{
@@ -225,7 +229,9 @@ func TestConfigValueFromHCL2Block(t *testing.T) {
 					},
 				},
 			},
-			map[string]interface{}{},
+			map[string]interface{}{
+				"address": map[string]interface{}{},
+			},
 		},
 		{
 			cty.NullVal(cty.EmptyObject),
@@ -234,8 +240,8 @@ func TestConfigValueFromHCL2Block(t *testing.T) {
 		},
 	}
 
-	for _, test := range tests {
-		t.Run(fmt.Sprintf("%#v", test.Input), func(t *testing.T) {
+	for i, test := range tests {
+		t.Run(fmt.Sprintf("%d-%#v", i, test.Input), func(t *testing.T) {
 			got := ConfigValueFromHCL2Block(test.Input, test.Schema)
 			if !reflect.DeepEqual(got, test.Want) {
 				t.Errorf("wrong result\ninput: %#v\ngot:   %#v\nwant:  %#v", test.Input, got, test.Want)