add implicit "id" to resource attribute schemas

When converting a legacy schemaMap to a configschema, we need to add
"id" as a required attribute to top-level resources if it's not
declared.

The "id" field will be required to interoperate with the legacy helper
schema, since the presence of an id was used to indicate the existence
of a resource.

helper/schema/core_schema.go

@@ -153,9 +153,29 @@ func (s *Schema) coreConfigSchemaType() cty.Type {
 	}
 }
 
-// CoreConfigSchema is a convenient shortcut for calling CoreConfigSchema
-// on the resource's schema.
+// CoreConfigSchema is a convenient shortcut for calling CoreConfigSchema on
+// the resource's schema. CoreConfigSchema adds the implicitly required "id"
+// attribute for top level resources if it doesn't exist.
 func (r *Resource) CoreConfigSchema() *configschema.Block {
+	block := r.coreConfigSchema()
+
+	if block.Attributes == nil {
+		block.Attributes = map[string]*configschema.Attribute{}
+	}
+
+	// Add the implicitly required "id" field if it doesn't exist
+	if block.Attributes["id"] == nil {
+		block.Attributes["id"] = &configschema.Attribute{
+			Type:     cty.String,
+			Optional: true,
+			Computed: true,
+		}
+	}
+
+	return block
+}
+
+func (r *Resource) coreConfigSchema() *configschema.Block {
 	return schemaMap(r.Schema).CoreConfigSchema()
 }
 

helper/schema/core_schema_test.go

@@ -1,16 +1,40 @@
 package schema
 
 import (
-	"reflect"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/zclconf/go-cty/cty"
 
-	"github.com/davecgh/go-spew/spew"
-
 	"github.com/hashicorp/terraform/configs/configschema"
 )
 
+var (
+	ignoreUnexported = cmpopts.IgnoreUnexported(cty.Type{})
+	equateEmpty      = cmpopts.EquateEmpty()
+)
+
+// add the implicit "id" attribute for test resources
+func testResource(block *configschema.Block) *configschema.Block {
+	if block.Attributes == nil {
+		block.Attributes = make(map[string]*configschema.Attribute)
+	}
+
+	if block.BlockTypes == nil {
+		block.BlockTypes = make(map[string]*configschema.NestedBlock)
+	}
+
+	if block.Attributes["id"] == nil {
+		block.Attributes["id"] = &configschema.Attribute{
+			Type:     cty.String,
+			Optional: true,
+			Computed: true,
+		}
+	}
+	return block
+}
+
 func TestSchemaMapCoreConfigSchema(t *testing.T) {
 	tests := map[string]struct {
 		Schema map[string]*Schema
@@ -18,7 +42,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 	}{
 		"empty": {
 			map[string]*Schema{},
-			&configschema.Block{},
+			testResource(&configschema.Block{}),
 		},
 		"primitives": {
 			map[string]*Schema{
@@ -41,7 +65,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					Computed: true,
 				},
 			},
-			&configschema.Block{
+			testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{
 					"int": {
 						Type:        cty.Number,
@@ -63,7 +87,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{},
-			},
+			}),
 		},
 		"simple collections": {
 			map[string]*Schema{
@@ -96,7 +120,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					// for pre-existing schemas.
 				},
 			},
-			&configschema.Block{
+			testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{
 					"list": {
 						Type:     cty.List(cty.Number),
@@ -116,7 +140,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{},
-			},
+			}),
 		},
 		"incorrectly-specified collections": {
 			// Historically we tolerated setting a type directly as the Elem
@@ -140,7 +164,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					Elem:     TypeBool,
 				},
 			},
-			&configschema.Block{
+			testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{
 					"list": {
 						Type:     cty.List(cty.Number),
@@ -156,7 +180,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{},
-			},
+			}),
 		},
 		"sub-resource collections": {
 			map[string]*Schema{
@@ -184,7 +208,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					},
 				},
 			},
-			&configschema.Block{
+			testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{},
 				BlockTypes: map[string]*configschema.NestedBlock{
 					"list": {
@@ -203,7 +227,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 						Block:   configschema.Block{},
 					},
 				},
-			},
+			}),
 		},
 		"nested attributes and blocks": {
 			map[string]*Schema{
@@ -233,7 +257,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					},
 				},
 			},
-			&configschema.Block{
+			testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{},
 				BlockTypes: map[string]*configschema.NestedBlock{
 					"foo": &configschema.NestedBlock{
@@ -255,7 +279,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 						MinItems: 1, // because schema is Required
 					},
 				},
-			},
+			}),
 		},
 		"sensitive": {
 			map[string]*Schema{
@@ -265,7 +289,7 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					Sensitive: true,
 				},
 			},
-			&configschema.Block{
+			testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{
 					"string": {
 						Type:      cty.String,
@@ -274,15 +298,15 @@ func TestSchemaMapCoreConfigSchema(t *testing.T) {
 					},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{},
-			},
+			}),
 		},
 	}
 
 	for name, test := range tests {
 		t.Run(name, func(t *testing.T) {
 			got := schemaMap(test.Schema).CoreConfigSchema()
-			if !reflect.DeepEqual(got, test.Want) {
-				t.Errorf("wrong result\ngot: %swant: %s", spew.Sdump(got), spew.Sdump(test.Want))
+			if !cmp.Equal(got, test.Want, equateEmpty, ignoreUnexported) {
+				cmp.Diff(got, test.Want, equateEmpty, ignoreUnexported)
 			}
 		})
 	}

helper/schema/provider_test.go

@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/davecgh/go-spew/spew"
+	"github.com/google/go-cmp/cmp"
 	"github.com/zclconf/go-cty/cty"
 
 	"github.com/hashicorp/terraform/config"
@@ -61,7 +61,7 @@ func TestProviderGetSchema(t *testing.T) {
 			BlockTypes: map[string]*configschema.NestedBlock{},
 		},
 		ResourceTypes: map[string]*configschema.Block{
-			"foo": &configschema.Block{
+			"foo": testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{
 					"bar": &configschema.Attribute{
 						Type:     cty.String,
@@ -69,10 +69,10 @@ func TestProviderGetSchema(t *testing.T) {
 					},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{},
-			},
+			}),
 		},
 		DataSources: map[string]*configschema.Block{
-			"baz": &configschema.Block{
+			"baz": testResource(&configschema.Block{
 				Attributes: map[string]*configschema.Attribute{
 					"bur": &configschema.Attribute{
 						Type:     cty.String,
@@ -80,7 +80,7 @@ func TestProviderGetSchema(t *testing.T) {
 					},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{},
-			},
+			}),
 		},
 	}
 	got, err := p.GetSchema(&terraform.ProviderSchemaRequest{
@@ -91,8 +91,8 @@ func TestProviderGetSchema(t *testing.T) {
 		t.Fatalf("unexpected error %s", err)
 	}
 
-	if !reflect.DeepEqual(got, want) {
-		t.Errorf("wrong result\ngot: %swant: %s", spew.Sdump(got), spew.Sdump(want))
+	if !cmp.Equal(got, want, equateEmpty, ignoreUnexported) {
+		t.Error("wrong result:\n", cmp.Diff(got, want, equateEmpty, ignoreUnexported))
 	}
 }