Add tests for extension resolver

This covers all lines except for panic-at-init ones that are just meant to signal programmer error.

internal/extensions/resolve_test.go

@@ -0,0 +1,127 @@
+// Copyright 2023-2024 Buf Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package extensions
+
+import (
+	"testing"
+
+	"buf.build/gen/go/bufbuild/protovalidate/protocolbuffers/go/buf/validate"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/encoding/protowire"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/types/descriptorpb"
+)
+
+func TestResolve(t *testing.T) {
+	t.Parallel()
+
+	expectedConstraints := &validate.FieldConstraints{
+		Cel: []*validate.Constraint{
+			{Message: proto.String("test")},
+		},
+	}
+	expectedConstraintsBytes, err := proto.Marshal(expectedConstraints)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name    string
+		builder func() proto.Message
+	}{
+		{
+			name: "Normal",
+			builder: func() proto.Message {
+				options := &descriptorpb.FieldOptions{}
+				proto.SetExtension(options, validate.E_Field, expectedConstraints)
+				return options
+			},
+		},
+		{
+			name: "Dynamic",
+			builder: func() proto.Message {
+				var unknownBytes []byte
+				unknownBytes = protowire.AppendTag(
+					unknownBytes,
+					validate.E_Field.TypeDescriptor().Number(),
+					protowire.BytesType,
+				)
+				unknownBytes = protowire.AppendBytes(
+					unknownBytes,
+					expectedConstraintsBytes,
+				)
+				options := &descriptorpb.FieldOptions{}
+				options.ProtoReflect().SetUnknown(protoreflect.RawFields(unknownBytes))
+				return options
+			},
+		},
+		{
+			name: "Unknown",
+			builder: func() proto.Message {
+				var unknownBytes []byte
+				unknownBytes = protowire.AppendTag(
+					unknownBytes,
+					validate.E_Field.TypeDescriptor().Number(),
+					protowire.BytesType,
+				)
+				unknownBytes = protowire.AppendBytes(
+					unknownBytes,
+					expectedConstraintsBytes,
+				)
+				options := &descriptorpb.FieldOptions{}
+				options.ProtoReflect().SetUnknown(protoreflect.RawFields(unknownBytes))
+				return options
+			},
+		},
+		{
+			name: "Legacy",
+			builder: func() proto.Message {
+				var unknownBytes []byte
+				unknownBytes = protowire.AppendTag(
+					unknownBytes,
+					legacyExtensionIndex,
+					protowire.BytesType,
+				)
+				unknownBytes = protowire.AppendBytes(
+					unknownBytes,
+					expectedConstraintsBytes,
+				)
+				options := &descriptorpb.FieldOptions{}
+				options.ProtoReflect().SetUnknown(protoreflect.RawFields(unknownBytes))
+				return options
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		test := tc
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			pb := test.builder()
+			extension := Resolve[*validate.FieldConstraints](pb, validate.E_Field)
+			require.NotNil(t, extension)
+			require.Equal(t, "test", extension.GetCel()[0].GetMessage())
+		})
+	}
+}
+
+func TestResolveNone(t *testing.T) {
+	t.Parallel()
+
+	require.Nil(t, Resolve[*validate.FieldConstraints](
+		&descriptorpb.FieldOptions{},
+		validate.E_Field,
+	))
+}