all: Refactor schema validation to support type-specific logic and pr…

…event AttributeTypes/ElementType field panics

Reference: #574
Reference: #699
Reference: #704
Reference: #705

The goal of this change is to enable easier schema validation within the framework logic. This is achieved by implementing new internal interfaces that implement shared logic across all schema types, then introduce methods on attribute types which currently implement type-specific validation logic.

The new `ValidateImplementation()` methods on attribute types, while technically exported, cannot be implemented externally due to their usage of internal types. This follows the existing implementation of the framework where attribute types already cannot be extended due to the `Equal(fwschema.Attribute)` method requirement. Therefore these new `ValidateImplementation()` methods do not need to worry about compatibility promises and can be modified or removed in the future.

This change also includes some breadcrumbs for other schema validation requests.

.changes/unreleased/BUG FIXES-20230329-102850.yaml

@@ -0,0 +1,7 @@
+kind: BUG FIXES
+body: 'datasource/schema: Raise errors with `ListAttribute`, `MapAttribute`, `ObjectAttribute`,
+  and `SetAttribute` implementations instead of panics when missing required `AttributeTypes` or
+  `ElementTypes` fields'
+time: 2023-03-29T10:28:50.525346-04:00
+custom:
+  Issue: "699"

.changes/unreleased/BUG FIXES-20230329-102851.yaml

@@ -0,0 +1,7 @@
+kind: BUG FIXES
+body: 'provider/metaschema: Raise errors with `ListAttribute`, `MapAttribute`, `ObjectAttribute`,
+  and `SetAttribute` implementations instead of panics when missing required `AttributeTypes` or
+  `ElementTypes` fields'
+time: 2023-03-29T10:28:51.525346-04:00
+custom:
+  Issue: "699"

.changes/unreleased/BUG FIXES-20230329-102852.yaml

@@ -0,0 +1,7 @@
+kind: BUG FIXES
+body: 'provider/schema: Raise errors with `ListAttribute`, `MapAttribute`, `ObjectAttribute`,
+  and `SetAttribute` implementations instead of panics when missing required `AttributeTypes` or
+  `ElementTypes` fields'
+time: 2023-03-29T10:28:52.525346-04:00
+custom:
+  Issue: "699"

.changes/unreleased/BUG FIXES-20230329-102853.yaml

@@ -0,0 +1,7 @@
+kind: BUG FIXES
+body: 'resource/schema: Raise errors with `ListAttribute`, `MapAttribute`, `ObjectAttribute`,
+  and `SetAttribute` implementations instead of panics when missing required `AttributeTypes` or
+  `ElementTypes` fields'
+time: 2023-03-29T10:28:53.525346-04:00
+custom:
+  Issue: "699"

.changes/unreleased/ENHANCEMENTS-20230329-102106.yaml

@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'datasource/schema: Added `Schema` type `ValidateImplementation()` method, which performs framework-defined
+  schema validation and can be used in unit testing'
+time: 2023-03-29T10:21:06.251285-04:00
+custom:
+  Issue: "699"

.changes/unreleased/ENHANCEMENTS-20230329-102107.yaml

@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'provider/metaschema: Added `Schema` type `ValidateImplementation()` method, which performs framework-defined
+  schema validation and can be used in unit testing'
+time: 2023-03-29T10:21:07.251285-04:00
+custom:
+  Issue: "699"

.changes/unreleased/ENHANCEMENTS-20230329-102108.yaml

@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'provider/schema: Added `Schema` type `ValidateImplementation()` method, which performs framework-defined
+  schema validation and can be used in unit testing'
+time: 2023-03-29T10:21:08.251285-04:00
+custom:
+  Issue: "699"

.changes/unreleased/ENHANCEMENTS-20230329-102109.yaml

@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'resource/schema: Added `Schema` type `ValidateImplementation()` method, which performs framework-defined
+  schema validation and can be used in unit testing'
+time: 2023-03-29T10:21:09.251285-04:00
+custom:
+  Issue: "699"

.changes/unreleased/NOTES-20230329-124336.yaml

@@ -0,0 +1,6 @@
+kind: NOTES
+body: 'datasource/schema: The `Schema` type `Validate()` method has been deprecated
+  in preference of `ValidateImplementation()`'
+time: 2023-03-29T12:43:36.636825-04:00
+custom:
+  Issue: "699"

.changes/unreleased/NOTES-20230329-124337.yaml

@@ -0,0 +1,6 @@
+kind: NOTES
+body: 'provider/metaschema: The `Schema` type `Validate()` method has been deprecated
+  in preference of `ValidateImplementation()`'
+time: 2023-03-29T12:43:37.636825-04:00
+custom:
+  Issue: "699"

.changes/unreleased/NOTES-20230329-124338.yaml

@@ -0,0 +1,6 @@
+kind: NOTES
+body: 'provider/schema: The `Schema` type `Validate()` method has been deprecated
+  in preference of `ValidateImplementation()`'
+time: 2023-03-29T12:43:38.636825-04:00
+custom:
+  Issue: "699"

.changes/unreleased/NOTES-20230329-124339.yaml

@@ -0,0 +1,6 @@
+kind: NOTES
+body: 'resource/schema: The `Schema` type `Validate()` method has been deprecated
+  in preference of `ValidateImplementation()`'
+time: 2023-03-29T12:43:39.636825-04:00
+custom:
+  Issue: "699"

datasource/schema/list_attribute.go

@@ -1,6 +1,8 @@
 package schema
 
 import (
+	"context"
+
 	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema/fwxschema"
@@ -12,8 +14,9 @@ import (
 
 // Ensure the implementation satisifies the desired interfaces.
 var (
-	_ Attribute                             = ListAttribute{}
-	_ fwxschema.AttributeWithListValidators = ListAttribute{}
+	_ Attribute                                    = ListAttribute{}
+	_ fwschema.AttributeWithValidateImplementation = ListAttribute{}
+	_ fwxschema.AttributeWithListValidators        = ListAttribute{}
 )
 
 // ListAttribute represents a schema attribute that is a list with a single
@@ -195,3 +198,13 @@ func (a ListAttribute) IsSensitive() bool {
 func (a ListAttribute) ListValidators() []validator.List {
 	return a.Validators
 }
+
+// ValidateImplementation contains logic for validating the
+// provider-defined implementation of the attribute to prevent unexpected
+// errors or panics. This logic runs during the GetProviderSchema RPC
+// and should never include false positives.
+func (a ListAttribute) ValidateImplementation(ctx context.Context, req fwschema.ValidateImplementationRequest, resp *fwschema.ValidateImplementationResponse) {
+	if a.CustomType == nil && a.ElementType == nil {
+		resp.Diagnostics.Append(fwschema.AttributeMissingElementTypeDiag(req.Path))
+	}
+}

datasource/schema/list_attribute_test.go

@@ -1,15 +1,19 @@
 package schema_test
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/datasource/schema"
+	"github.com/hashicorp/terraform-plugin-framework/diag"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema"
 	"github.com/hashicorp/terraform-plugin-framework/internal/testing/testschema"
+	testtypes "github.com/hashicorp/terraform-plugin-framework/internal/testing/types"
+	"github.com/hashicorp/terraform-plugin-framework/path"
 	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
 	"github.com/hashicorp/terraform-plugin-framework/types"
 	"github.com/hashicorp/terraform-plugin-go/tftypes"
@@ -424,3 +428,71 @@ func TestListAttributeListValidators(t *testing.T) {
 		})
 	}
 }
+
+func TestListAttributeValidateImplementation(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		attribute schema.ListAttribute
+		request   fwschema.ValidateImplementationRequest
+		expected  *fwschema.ValidateImplementationResponse
+	}{
+		"customtype": {
+			attribute: schema.ListAttribute{
+				Computed:   true,
+				CustomType: testtypes.ListType{},
+			},
+			request: fwschema.ValidateImplementationRequest{
+				Name: "test",
+				Path: path.Root("test"),
+			},
+			expected: &fwschema.ValidateImplementationResponse{},
+		},
+		"elementtype": {
+			attribute: schema.ListAttribute{
+				Computed:    true,
+				ElementType: types.StringType,
+			},
+			request: fwschema.ValidateImplementationRequest{
+				Name: "test",
+				Path: path.Root("test"),
+			},
+			expected: &fwschema.ValidateImplementationResponse{},
+		},
+		"elementtype-missing": {
+			attribute: schema.ListAttribute{
+				Computed: true,
+			},
+			request: fwschema.ValidateImplementationRequest{
+				Name: "test",
+				Path: path.Root("test"),
+			},
+			expected: &fwschema.ValidateImplementationResponse{
+				Diagnostics: diag.Diagnostics{
+					diag.NewErrorDiagnostic(
+						"Invalid Attribute Implementation",
+						"When validating the schema, an implementation issue was found. "+
+							"This is always an issue with the provider and should be reported to the provider developers.\n\n"+
+							"\"test\" is missing the CustomType or ElementType field on a collection Attribute. "+
+							"One of these fields is required to prevent other unexpected errors or panics.",
+					),
+				},
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		name, testCase := name, testCase
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := &fwschema.ValidateImplementationResponse{}
+			testCase.attribute.ValidateImplementation(context.Background(), testCase.request, got)
+
+			if diff := cmp.Diff(got, testCase.expected); diff != "" {
+				t.Errorf("unexpected difference: %s", diff)
+			}
+		})
+	}
+}

datasource/schema/map_attribute.go

@@ -1,6 +1,8 @@
 package schema
 
 import (
+	"context"
+
 	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema/fwxschema"
@@ -12,8 +14,9 @@ import (
 
 // Ensure the implementation satisifies the desired interfaces.
 var (
-	_ Attribute                            = MapAttribute{}
-	_ fwxschema.AttributeWithMapValidators = MapAttribute{}
+	_ Attribute                                    = MapAttribute{}
+	_ fwschema.AttributeWithValidateImplementation = MapAttribute{}
+	_ fwxschema.AttributeWithMapValidators         = MapAttribute{}
 )
 
 // MapAttribute represents a schema attribute that is a list with a single
@@ -198,3 +201,13 @@ func (a MapAttribute) IsSensitive() bool {
 func (a MapAttribute) MapValidators() []validator.Map {
 	return a.Validators
 }
+
+// ValidateImplementation contains logic for validating the
+// provider-defined implementation of the attribute to prevent unexpected
+// errors or panics. This logic runs during the GetProviderSchema RPC
+// and should never include false positives.
+func (a MapAttribute) ValidateImplementation(ctx context.Context, req fwschema.ValidateImplementationRequest, resp *fwschema.ValidateImplementationResponse) {
+	if a.CustomType == nil && a.ElementType == nil {
+		resp.Diagnostics.Append(fwschema.AttributeMissingElementTypeDiag(req.Path))
+	}
+}

datasource/schema/map_attribute_test.go

@@ -1,15 +1,19 @@
 package schema_test
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/datasource/schema"
+	"github.com/hashicorp/terraform-plugin-framework/diag"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema"
 	"github.com/hashicorp/terraform-plugin-framework/internal/testing/testschema"
+	testtypes "github.com/hashicorp/terraform-plugin-framework/internal/testing/types"
+	"github.com/hashicorp/terraform-plugin-framework/path"
 	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
 	"github.com/hashicorp/terraform-plugin-framework/types"
 	"github.com/hashicorp/terraform-plugin-go/tftypes"
@@ -424,3 +428,71 @@ func TestMapAttributeMapValidators(t *testing.T) {
 		})
 	}
 }
+
+func TestMapAttributeValidateImplementation(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		attribute schema.MapAttribute
+		request   fwschema.ValidateImplementationRequest
+		expected  *fwschema.ValidateImplementationResponse
+	}{
+		"customtype": {
+			attribute: schema.MapAttribute{
+				Computed:   true,
+				CustomType: testtypes.MapType{},
+			},
+			request: fwschema.ValidateImplementationRequest{
+				Name: "test",
+				Path: path.Root("test"),
+			},
+			expected: &fwschema.ValidateImplementationResponse{},
+		},
+		"elementtype": {
+			attribute: schema.MapAttribute{
+				Computed:    true,
+				ElementType: types.StringType,
+			},
+			request: fwschema.ValidateImplementationRequest{
+				Name: "test",
+				Path: path.Root("test"),
+			},
+			expected: &fwschema.ValidateImplementationResponse{},
+		},
+		"elementtype-missing": {
+			attribute: schema.MapAttribute{
+				Computed: true,
+			},
+			request: fwschema.ValidateImplementationRequest{
+				Name: "test",
+				Path: path.Root("test"),
+			},
+			expected: &fwschema.ValidateImplementationResponse{
+				Diagnostics: diag.Diagnostics{
+					diag.NewErrorDiagnostic(
+						"Invalid Attribute Implementation",
+						"When validating the schema, an implementation issue was found. "+
+							"This is always an issue with the provider and should be reported to the provider developers.\n\n"+
+							"\"test\" is missing the CustomType or ElementType field on a collection Attribute. "+
+							"One of these fields is required to prevent other unexpected errors or panics.",
+					),
+				},
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		name, testCase := name, testCase
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := &fwschema.ValidateImplementationResponse{}
+			testCase.attribute.ValidateImplementation(context.Background(), testCase.request, got)
+
+			if diff := cmp.Diff(got, testCase.expected); diff != "" {
+				t.Errorf("unexpected difference: %s", diff)
+			}
+		})
+	}
+}

datasource/schema/object_attribute.go

@@ -1,6 +1,8 @@
 package schema
 
 import (
+	"context"
+
 	"github.com/hashicorp/terraform-plugin-framework/attr"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema"
 	"github.com/hashicorp/terraform-plugin-framework/internal/fwschema/fwxschema"
@@ -12,8 +14,9 @@ import (
 
 // Ensure the implementation satisifies the desired interfaces.
 var (
-	_ Attribute                               = ObjectAttribute{}
-	_ fwxschema.AttributeWithObjectValidators = ObjectAttribute{}
+	_ Attribute                                    = ObjectAttribute{}
+	_ fwschema.AttributeWithValidateImplementation = ObjectAttribute{}
+	_ fwxschema.AttributeWithObjectValidators      = ObjectAttribute{}
 )
 
 // ObjectAttribute represents a schema attribute that is an object with only
@@ -197,3 +200,13 @@ func (a ObjectAttribute) IsSensitive() bool {
 func (a ObjectAttribute) ObjectValidators() []validator.Object {
 	return a.Validators
 }
+
+// ValidateImplementation contains logic for validating the
+// provider-defined implementation of the attribute to prevent unexpected
+// errors or panics. This logic runs during the GetProviderSchema RPC
+// and should never include false positives.
+func (a ObjectAttribute) ValidateImplementation(ctx context.Context, req fwschema.ValidateImplementationRequest, resp *fwschema.ValidateImplementationResponse) {
+	if a.AttributeTypes == nil && a.CustomType == nil {
+		resp.Diagnostics.Append(fwschema.AttributeMissingAttributeTypesDiag(req.Path))
+	}
+}