boolvalidator: add Equals validator (#232)

* boolvalidator: add Equals validator

This validator can be used in cases where non-null boolean value should be exactly `true` or exactly `false`.

```console
% go test -count=1 ./boolvalidator/...
ok      github.com/hashicorp/terraform-plugin-framework-validators/boolvalidator        0.251s
```

* Update boolvalidator/equals.go

Co-authored-by: Austin Valle <[email protected]>

* chore: changelog

Author: jar-b

.changes/unreleased/FEATURES-20240920-164852.yaml

@@ -0,0 +1,5 @@
+kind: FEATURES
+body: 'boolvalidator: Added `Equals` validator'
+time: 2024-09-20T16:48:52.562758-04:00
+custom:
+    Issue: "232"

boolvalidator/equals.go

@@ -0,0 +1,51 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package boolvalidator
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-framework-validators/helpers/validatordiag"
+	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+)
+
+var _ validator.Bool = equalsValidator{}
+
+type equalsValidator struct {
+	value types.Bool
+}
+
+func (v equalsValidator) Description(ctx context.Context) string {
+	return fmt.Sprintf("Value must be %q", v.value)
+}
+
+func (v equalsValidator) MarkdownDescription(ctx context.Context) string {
+	return v.Description(ctx)
+}
+
+func (v equalsValidator) ValidateBool(ctx context.Context, req validator.BoolRequest, resp *validator.BoolResponse) {
+	if req.ConfigValue.IsNull() || req.ConfigValue.IsUnknown() {
+		return
+	}
+
+	configValue := req.ConfigValue
+
+	if !configValue.Equal(v.value) {
+		resp.Diagnostics.Append(validatordiag.InvalidAttributeValueMatchDiagnostic(
+			req.Path,
+			v.Description(ctx),
+			configValue.String(),
+		))
+	}
+}
+
+// Equals returns an AttributeValidator which ensures that the configured boolean attribute
+// matches the given `value`. Null (unconfigured) and unknown (known after apply) values are skipped.
+func Equals(value bool) validator.Bool {
+	return equalsValidator{
+		value: types.BoolValue(value),
+	}
+}

boolvalidator/equals_test.go

@@ -0,0 +1,69 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package boolvalidator_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-framework-validators/boolvalidator"
+	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+)
+
+func TestEqualsValidator(t *testing.T) {
+	t.Parallel()
+
+	type testCase struct {
+		in        types.Bool
+		validator validator.Bool
+		expErrors int
+	}
+
+	testCases := map[string]testCase{
+		"simple-match": {
+			in:        types.BoolValue(true),
+			validator: boolvalidator.Equals(true),
+			expErrors: 0,
+		},
+		"simple-mismatch": {
+			in:        types.BoolValue(false),
+			validator: boolvalidator.Equals(true),
+			expErrors: 1,
+		},
+		"skip-validation-on-null": {
+			in:        types.BoolNull(),
+			validator: boolvalidator.Equals(true),
+			expErrors: 0,
+		},
+		"skip-validation-on-unknown": {
+			in:        types.BoolUnknown(),
+			validator: boolvalidator.Equals(true),
+			expErrors: 0,
+		},
+	}
+
+	for name, test := range testCases {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			req := validator.BoolRequest{
+				ConfigValue: test.in,
+			}
+			res := validator.BoolResponse{}
+			test.validator.ValidateBool(context.TODO(), req, &res)
+
+			if test.expErrors > 0 && !res.Diagnostics.HasError() {
+				t.Fatalf("expected %d error(s), got none", test.expErrors)
+			}
+
+			if test.expErrors > 0 && test.expErrors != res.Diagnostics.ErrorsCount() {
+				t.Fatalf("expected %d error(s), got %d: %v", test.expErrors, res.Diagnostics.ErrorsCount(), res.Diagnostics)
+			}
+
+			if test.expErrors == 0 && res.Diagnostics.HasError() {
+				t.Fatalf("expected no error(s), got %d: %v", res.Diagnostics.ErrorsCount(), res.Diagnostics)
+			}
+		})
+	}
+}