feat: Experiment override service

pkg/decision/experiment_override_service.go

@@ -0,0 +1,93 @@
+/****************************************************************************
+ * Copyright 2019, Optimizely, Inc. and contributors                        *
+ *                                                                          *
+ * 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 decision //
+package decision
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/optimizely/go-sdk/pkg/decision/reasons"
+	"github.com/optimizely/go-sdk/pkg/entities"
+	"github.com/optimizely/go-sdk/pkg/logging"
+)
+
+var eosLogger = logging.GetLogger("ExperimentOverrideService")
+
+// ExperimentOverrideKey represents the user ID and experiment associated with an override variation
+type ExperimentOverrideKey struct {
+	ExperimentKey, UserID string
+}
+
+// ExperimentOverrideStore provides read access to overrides
+type ExperimentOverrideStore interface {
+	// Returns a variation associated with overrideKey
+	GetVariation(overrideKey ExperimentOverrideKey) (string, bool)
+}
+
+// MapOverridesStore is a map-based implementation of OverrideStore
+type MapOverridesStore struct {
+	overridesMap map[ExperimentOverrideKey]string
+}
+
+// GetVariation returns the override associated with the given key in the map
+func (m *MapOverridesStore) GetVariation(overrideKey ExperimentOverrideKey) (string, bool) {
+	variationKey, ok := m.overridesMap[overrideKey]
+	return variationKey, ok
+}
+
+// ExperimentOverrideService makes a decision using an ExperimentOverridesStore
+// Implements the ExperimentService interface
+type ExperimentOverrideService struct {
+	Overrides ExperimentOverrideStore
+}
+
+// NewExperimentOverrideService returns a pointer to an initialized ExperimentOverrideService
+func NewExperimentOverrideService(overrides ExperimentOverrideStore) *ExperimentOverrideService {
+	return &ExperimentOverrideService{
+		Overrides: overrides,
+	}
+}
+
+// GetDecision returns a decision with a variation when the store returns a variation assignment for the given user and experiment
+func (s ExperimentOverrideService) GetDecision(decisionContext ExperimentDecisionContext, userContext entities.UserContext) (ExperimentDecision, error) {
+	decision := ExperimentDecision{}
+
+	if decisionContext.Experiment == nil {
+		return decision, errors.New("decisionContext Experiment is nil")
+	}
+
+	variationKey, ok := s.Overrides.GetVariation(ExperimentOverrideKey{ExperimentKey: decisionContext.Experiment.Key, UserID: userContext.ID})
+	if !ok {
+		decision.Reason = reasons.NoOverrideVariationAssignment
+		return decision, nil
+	}
+
+	// TODO(Matt): Add a VariationsByKey map to the Experiment struct, and use it to look up Variation by key
+	for _, variation := range decisionContext.Experiment.Variations {
+		variation := variation
+		if variation.Key == variationKey {
+			decision.Variation = &variation
+			decision.Reason = reasons.OverrideVariationAssignmentFound
+			eosLogger.Info(fmt.Sprintf("Override variation %v found for user %v", variationKey, userContext.ID))
+			return decision, nil
+		}
+	}
+
+	decision.Reason = reasons.InvalidOverrideVariationAssignment
+	return decision, nil
+}

pkg/decision/experiment_override_service_test.go

@@ -0,0 +1,137 @@
+/****************************************************************************
+ * Copyright 2019, Optimizely, Inc. and contributors                        *
+ *                                                                          *
+ * 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 decision //
+package decision
+
+import (
+	"testing"
+
+	"github.com/optimizely/go-sdk/pkg/decision/reasons"
+	"github.com/optimizely/go-sdk/pkg/entities"
+	"github.com/stretchr/testify/suite"
+)
+
+type ExperimentOverrideServiceTestSuite struct {
+	suite.Suite
+	mockConfig      *mockProjectConfig
+	overrides       map[ExperimentOverrideKey]string
+	overrideService *ExperimentOverrideService
+}
+
+func (s *ExperimentOverrideServiceTestSuite) SetupTest() {
+	s.mockConfig = new(mockProjectConfig)
+	s.overrides = make(map[ExperimentOverrideKey]string)
+	s.overrideService = NewExperimentOverrideService(&MapOverridesStore{
+		overridesMap: s.overrides,
+	})
+}
+
+func (s *ExperimentOverrideServiceTestSuite) TestOverridesIncludeVariation() {
+	testDecisionContext := ExperimentDecisionContext{
+		Experiment:    &testExp1111,
+		ProjectConfig: s.mockConfig,
+	}
+	testUserContext := entities.UserContext{
+		ID: "test_user_1",
+	}
+	s.overrides[ExperimentOverrideKey{ExperimentKey: testExp1111.Key, UserID: "test_user_1"}] = testExp1111Var2222.Key
+	decision, err := s.overrideService.GetDecision(testDecisionContext, testUserContext)
+	s.NoError(err)
+	s.NotNil(decision.Variation)
+	s.Exactly(testExp1111Var2222.Key, decision.Variation.Key)
+	s.Exactly(reasons.OverrideVariationAssignmentFound, decision.Reason)
+}
+
+func (s *ExperimentOverrideServiceTestSuite) TestNilDecisionContextExperiment() {
+	testDecisionContext := ExperimentDecisionContext{
+		ProjectConfig: s.mockConfig,
+	}
+	testUserContext := entities.UserContext{
+		ID: "test_user_1",
+	}
+	decision, err := s.overrideService.GetDecision(testDecisionContext, testUserContext)
+	s.Error(err)
+	s.Nil(decision.Variation)
+}
+
+func (s *ExperimentOverrideServiceTestSuite) TestNoOverrideForExperiment() {
+	testDecisionContext := ExperimentDecisionContext{
+		Experiment:    &testExp1111,
+		ProjectConfig: s.mockConfig,
+	}
+	testUserContext := entities.UserContext{
+		ID: "test_user_1",
+	}
+	// The decision context refers to testExp1111, but this override is for another experiment
+	s.overrides[ExperimentOverrideKey{ExperimentKey: testExp1113.Key, UserID: "test_user_1"}] = testExp1113Var2224.Key
+	decision, err := s.overrideService.GetDecision(testDecisionContext, testUserContext)
+	s.NoError(err)
+	s.Nil(decision.Variation)
+	s.Exactly(reasons.NoOverrideVariationAssignment, decision.Reason)
+}
+
+func (s *ExperimentOverrideServiceTestSuite) TestNoOverrideForUser() {
+	testDecisionContext := ExperimentDecisionContext{
+		Experiment:    &testExp1111,
+		ProjectConfig: s.mockConfig,
+	}
+	testUserContext := entities.UserContext{
+		ID: "test_user_1",
+	}
+	// The user context refers to "test_user_1", but this override is for another user
+	s.overrides[ExperimentOverrideKey{ExperimentKey: testExp1111.Key, UserID: "test_user_2"}] = testExp1111Var2222.Key
+	decision, err := s.overrideService.GetDecision(testDecisionContext, testUserContext)
+	s.NoError(err)
+	s.Nil(decision.Variation)
+	s.Exactly(reasons.NoOverrideVariationAssignment, decision.Reason)
+}
+
+func (s *ExperimentOverrideServiceTestSuite) TestNoOverrideForUserOrExperiment() {
+	testDecisionContext := ExperimentDecisionContext{
+		Experiment:    &testExp1111,
+		ProjectConfig: s.mockConfig,
+	}
+	testUserContext := entities.UserContext{
+		ID: "test_user_1",
+	}
+	// This override is for both a different user and a different experiment than the ones in the contexts above
+	s.overrides[ExperimentOverrideKey{ExperimentKey: testExp1113.Key, UserID: "test_user_3"}] = testExp1111Var2222.Key
+	decision, err := s.overrideService.GetDecision(testDecisionContext, testUserContext)
+	s.NoError(err)
+	s.Nil(decision.Variation)
+	s.Exactly(reasons.NoOverrideVariationAssignment, decision.Reason)
+}
+
+func (s *ExperimentOverrideServiceTestSuite) TestInvalidVariationInOverride() {
+	testDecisionContext := ExperimentDecisionContext{
+		Experiment:    &testExp1111,
+		ProjectConfig: s.mockConfig,
+	}
+	testUserContext := entities.UserContext{
+		ID: "test_user_1",
+	}
+	// This override variation key does not exist in the experiment
+	s.overrides[ExperimentOverrideKey{ExperimentKey: testExp1111.Key, UserID: "test_user_1"}] = "invalid_variation_key"
+	decision, err := s.overrideService.GetDecision(testDecisionContext, testUserContext)
+	s.NoError(err)
+	s.Nil(decision.Variation)
+	s.Exactly(reasons.InvalidOverrideVariationAssignment, decision.Reason)
+}
+
+func TestExperimentOverridesTestSuite(t *testing.T) {
+	suite.Run(t, new(ExperimentOverrideServiceTestSuite))
+}

pkg/decision/reasons/reason.go

@@ -43,4 +43,10 @@ const (
 	InvalidWhitelistVariationAssignment Reason = "Invalid whitelist variation assignment"
 	// WhitelistVariationAssignmentFound - a valid variation assignment was found for the given user and experiment
 	WhitelistVariationAssignmentFound Reason = "Whitelist variation assignment found"
+	// NoOverrideVariationAssignment - No override variation was found for the given user and experiment
+	NoOverrideVariationAssignment Reason = "No override variation assignment"
+	// InvalidOverrideVariationAssignment - An override variation was found for the given user and experiment, but no variation with that key exists in the given experiment
+	InvalidOverrideVariationAssignment Reason = "Invalid override variation assignment"
+	// OverrideVariationAssignmentFound - A valid override variation was found for the given user and experiment
+	OverrideVariationAssignmentFound Reason = "Override variation assignment found"
 )