tfprotov5+tfprotov6: Add DynamicValue type IsNull method (#306)

Reference: #305
hashicorp · Jun 28, 2023 · e339254 · e339254
1 parent 18c198e
commit e339254
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diff --git a/.changes/unreleased/ENHANCEMENTS-20230627-125806.yaml b/.changes/unreleased/ENHANCEMENTS-20230627-125806.yaml
@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'tfprotov5: Added `DynamicValue` type `IsNull` method, which enables checking
+  if the value is null without type information and fully decoding underlying data'
+time: 2023-06-27T12:58:06.917152-04:00
+custom:
+  Issue: "305"
diff --git a/.changes/unreleased/ENHANCEMENTS-20230627-125912.yaml b/.changes/unreleased/ENHANCEMENTS-20230627-125912.yaml
@@ -0,0 +1,6 @@
+kind: ENHANCEMENTS
+body: 'tfprotov6: Added `DynamicValue` type `IsNull` method, which enables checking
+  if the value is null without type information and fully decoding underlying data'
+time: 2023-06-27T12:59:12.941648-04:00
+custom:
+  Issue: "305"
diff --git a/tfprotov5/dynamic_value.go b/tfprotov5/dynamic_value.go
@@ -4,9 +4,14 @@
 package tfprotov5
 
 import (
+	"bytes"
+	"encoding/json"
 	"errors"
+	"fmt"
 
 	"github.com/hashicorp/terraform-plugin-go/tftypes"
+	msgpack "github.com/vmihailenco/msgpack/v5"
+	"github.com/vmihailenco/msgpack/v5/msgpcode"
 )
 
 // ErrUnknownDynamicValueType is returned when a DynamicValue has no MsgPack or
@@ -47,6 +52,43 @@ type DynamicValue struct {
 	JSON    []byte
 }
 
+// IsNull returns true if the DynamicValue represents a null value based on the
+// underlying JSON or MessagePack data.
+func (d DynamicValue) IsNull() (bool, error) {
+	if d.JSON != nil {
+		decoder := json.NewDecoder(bytes.NewReader(d.JSON))
+		token, err := decoder.Token()
+
+		if err != nil {
+			return false, fmt.Errorf("unable to read DynamicValue JSON token: %w", err)
+		}
+
+		if token != nil {
+			return false, nil
+		}
+
+		return true, nil
+	}
+
+	if d.MsgPack != nil {
+		decoder := msgpack.NewDecoder(bytes.NewReader(d.MsgPack))
+		code, err := decoder.PeekCode()
+
+		if err != nil {
+			return false, fmt.Errorf("unable to read DynamicValue MsgPack code: %w", err)
+		}
+
+		// Extensions are considered unknown
+		if msgpcode.IsExt(code) || code != msgpcode.Nil {
+			return false, nil
+		}
+
+		return true, nil
+	}
+
+	return false, fmt.Errorf("unable to read DynamicValue: %w", ErrUnknownDynamicValueType)
+}
+
 // Unmarshal returns a `tftypes.Value` that represents the information
 // contained in the DynamicValue in an easy-to-interact-with way. It is the
 // main purpose of the DynamicValue type, and is how provider developers should

diff --git a/tfprotov5/dynamic_value_test.go b/tfprotov5/dynamic_value_test.go
@@ -0,0 +1,107 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package tfprotov5_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+func TestDynamicValueIsNull(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		dynamicValue  tfprotov5.DynamicValue
+		expected      bool
+		expectedError error
+	}{
+		"empty-dynamic-value": {
+			dynamicValue:  tfprotov5.DynamicValue{},
+			expected:      false,
+			expectedError: fmt.Errorf("unable to read DynamicValue: DynamicValue had no JSON or msgpack data set"),
+		},
+		"null": {
+			dynamicValue: testNewDynamicValueMust(t,
+				tftypes.Object{
+					AttributeTypes: map[string]tftypes.Type{
+						"test_string_attribute": tftypes.String,
+					},
+				},
+				tftypes.NewValue(
+					tftypes.Object{
+						AttributeTypes: map[string]tftypes.Type{
+							"test_string_attribute": tftypes.String,
+						},
+					},
+					nil,
+				),
+			),
+			expected: true,
+		},
+		"known": {
+			dynamicValue: testNewDynamicValueMust(t,
+				tftypes.Object{
+					AttributeTypes: map[string]tftypes.Type{
+						"test_string_attribute": tftypes.String,
+					},
+				},
+				tftypes.NewValue(
+					tftypes.Object{
+						AttributeTypes: map[string]tftypes.Type{
+							"test_string_attribute": tftypes.String,
+						},
+					},
+					map[string]tftypes.Value{
+						"test_string_attribute": tftypes.NewValue(tftypes.String, "test-value"),
+					},
+				),
+			),
+			expected: false,
+		},
+	}
+
+	for name, testCase := range testCases {
+		name, testCase := name, testCase
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got, err := testCase.dynamicValue.IsNull()
+
+			if err != nil {
+				if testCase.expectedError == nil {
+					t.Fatalf("wanted no error, got error: %s", err)
+				}
+
+				if !strings.Contains(err.Error(), testCase.expectedError.Error()) {
+					t.Fatalf("wanted error %q, got error: %s", testCase.expectedError.Error(), err.Error())
+				}
+			}
+
+			if err == nil && testCase.expectedError != nil {
+				t.Fatalf("got no error, wanted err: %s", testCase.expectedError)
+			}
+
+			if got != testCase.expected {
+				t.Errorf("expected %t, got %t", testCase.expected, got)
+			}
+		})
+	}
+}
+
+func testNewDynamicValueMust(t *testing.T, typ tftypes.Type, value tftypes.Value) tfprotov5.DynamicValue {
+	t.Helper()
+
+	dynamicValue, err := tfprotov5.NewDynamicValue(typ, value)
+
+	if err != nil {
+		t.Fatalf("unable to create DynamicValue: %s", err)
+	}
+
+	return dynamicValue
+}
diff --git a/tfprotov6/dynamic_value.go b/tfprotov6/dynamic_value.go
@@ -4,9 +4,14 @@
 package tfprotov6
 
 import (
+	"bytes"
+	"encoding/json"
 	"errors"
+	"fmt"
 
 	"github.com/hashicorp/terraform-plugin-go/tftypes"
+	msgpack "github.com/vmihailenco/msgpack/v5"
+	"github.com/vmihailenco/msgpack/v5/msgpcode"
 )
 
 // ErrUnknownDynamicValueType is returned when a DynamicValue has no MsgPack or
@@ -47,6 +52,43 @@ type DynamicValue struct {
 	JSON    []byte
 }
 
+// IsNull returns true if the DynamicValue represents a null value based on the
+// underlying JSON or MessagePack data.
+func (d DynamicValue) IsNull() (bool, error) {
+	if d.JSON != nil {
+		decoder := json.NewDecoder(bytes.NewReader(d.JSON))
+		token, err := decoder.Token()
+
+		if err != nil {
+			return false, fmt.Errorf("unable to read DynamicValue JSON token: %w", err)
+		}
+
+		if token != nil {
+			return false, nil
+		}
+
+		return true, nil
+	}
+
+	if d.MsgPack != nil {
+		decoder := msgpack.NewDecoder(bytes.NewReader(d.MsgPack))
+		code, err := decoder.PeekCode()
+
+		if err != nil {
+			return false, fmt.Errorf("unable to read DynamicValue MsgPack code: %w", err)
+		}
+
+		// Extensions are considered unknown
+		if msgpcode.IsExt(code) || code != msgpcode.Nil {
+			return false, nil
+		}
+
+		return true, nil
+	}
+
+	return false, fmt.Errorf("unable to read DynamicValue: %w", ErrUnknownDynamicValueType)
+}
+
 // Unmarshal returns a `tftypes.Value` that represents the information
 // contained in the DynamicValue in an easy-to-interact-with way. It is the
 // main purpose of the DynamicValue type, and is how provider developers should

diff --git a/tfprotov6/dynamic_value_test.go b/tfprotov6/dynamic_value_test.go
@@ -0,0 +1,107 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package tfprotov6_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov6"
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+func TestDynamicValueIsNull(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		dynamicValue  tfprotov6.DynamicValue
+		expected      bool
+		expectedError error
+	}{
+		"empty-dynamic-value": {
+			dynamicValue:  tfprotov6.DynamicValue{},
+			expected:      false,
+			expectedError: fmt.Errorf("unable to read DynamicValue: DynamicValue had no JSON or msgpack data set"),
+		},
+		"null": {
+			dynamicValue: testNewDynamicValueMust(t,
+				tftypes.Object{
+					AttributeTypes: map[string]tftypes.Type{
+						"test_string_attribute": tftypes.String,
+					},
+				},
+				tftypes.NewValue(
+					tftypes.Object{
+						AttributeTypes: map[string]tftypes.Type{
+							"test_string_attribute": tftypes.String,
+						},
+					},
+					nil,
+				),
+			),
+			expected: true,
+		},
+		"known": {
+			dynamicValue: testNewDynamicValueMust(t,
+				tftypes.Object{
+					AttributeTypes: map[string]tftypes.Type{
+						"test_string_attribute": tftypes.String,
+					},
+				},
+				tftypes.NewValue(
+					tftypes.Object{
+						AttributeTypes: map[string]tftypes.Type{
+							"test_string_attribute": tftypes.String,
+						},
+					},
+					map[string]tftypes.Value{
+						"test_string_attribute": tftypes.NewValue(tftypes.String, "test-value"),
+					},
+				),
+			),
+			expected: false,
+		},
+	}
+
+	for name, testCase := range testCases {
+		name, testCase := name, testCase
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got, err := testCase.dynamicValue.IsNull()
+
+			if err != nil {
+				if testCase.expectedError == nil {
+					t.Fatalf("wanted no error, got error: %s", err)
+				}
+
+				if !strings.Contains(err.Error(), testCase.expectedError.Error()) {
+					t.Fatalf("wanted error %q, got error: %s", testCase.expectedError.Error(), err.Error())
+				}
+			}
+
+			if err == nil && testCase.expectedError != nil {
+				t.Fatalf("got no error, wanted err: %s", testCase.expectedError)
+			}
+
+			if got != testCase.expected {
+				t.Errorf("expected %t, got %t", testCase.expected, got)
+			}
+		})
+	}
+}
+
+func testNewDynamicValueMust(t *testing.T, typ tftypes.Type, value tftypes.Value) tfprotov6.DynamicValue {
+	t.Helper()
+
+	dynamicValue, err := tfprotov6.NewDynamicValue(typ, value)
+
+	if err != nil {
+		t.Fatalf("unable to create DynamicValue: %s", err)
+	}
+
+	return dynamicValue
+}