Added fallback treatment and calculator

Author: nmayorsplit

dtos/fallbacktreatment.go

@@ -0,0 +1,63 @@
+package dtos
+
+const (
+	labelPrefix = "fallback - "
+)
+
+type FallbackTreatment struct {
+	Treatment string
+	Config    string
+	Label     *string
+}
+
+type FallbackTreatmentConfig struct {
+	GlobalFallbackTreatment *FallbackTreatment
+	byFlagFallbackTreatment map[string]FallbackTreatment
+}
+
+type FallbackTreatmentCalculator interface {
+	Resolve(flagName string, label string) FallbackTreatment
+}
+
+type FallbackTreatmentCalculatorImp struct {
+	fallbackTreatmentConfig *FallbackTreatmentConfig
+}
+
+func NewFallbackTreatmentCalculatorImp(fallbackTreatmentConfig *FallbackTreatmentConfig) FallbackTreatmentCalculatorImp {
+	return FallbackTreatmentCalculatorImp{
+		fallbackTreatmentConfig: fallbackTreatmentConfig,
+	}
+}
+
+func (f *FallbackTreatmentCalculatorImp) Resolve(flagName string, label *string) FallbackTreatment {
+	if f.fallbackTreatmentConfig != nil {
+		if byFlag := f.fallbackTreatmentConfig.byFlagFallbackTreatment; byFlag != nil {
+			if val, ok := byFlag[flagName]; ok {
+				return FallbackTreatment{
+					Treatment: val.Treatment,
+					Config:    val.Config,
+					Label:     f.resolveLabel(label),
+				}
+			}
+		}
+		if f.fallbackTreatmentConfig.GlobalFallbackTreatment != nil {
+			return FallbackTreatment{
+				Treatment: f.fallbackTreatmentConfig.GlobalFallbackTreatment.Treatment,
+				Config:    f.fallbackTreatmentConfig.GlobalFallbackTreatment.Config,
+				Label:     f.resolveLabel(label),
+			}
+		}
+	}
+	return FallbackTreatment{
+		Treatment: "control",
+		Label:     label,
+	}
+}
+
+func (f *FallbackTreatmentCalculatorImp) resolveLabel(label *string) *string {
+	if label == nil {
+		return nil
+	}
+	result := labelPrefix + *label
+	return &result
+}

dtos/fallbacktreatment_test.go

@@ -0,0 +1,63 @@
+package dtos
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFallbackTreatmentCalculatorResolve(t *testing.T) {
+	// Initial setup with both global and flag-specific treatments
+	config := &FallbackTreatmentConfig{
+		GlobalFallbackTreatment: &FallbackTreatment{
+			Treatment: "global_treatment",
+			Config:    "global_config",
+		},
+		byFlagFallbackTreatment: map[string]FallbackTreatment{
+			"flag1": {
+				Treatment: "flag1_treatment",
+				Config:    "flag1_config",
+			},
+		},
+	}
+	calc := NewFallbackTreatmentCalculatorImp(config)
+
+	// Test flag-specific treatment with label
+	label := "some_label"
+	result := calc.Resolve("flag1", &label)
+	assert.Equal(t, "flag1_treatment", result.Treatment)
+	assert.Equal(t, "flag1_config", result.Config)
+	assert.Equal(t, "fallback - some_label", *result.Label)
+
+	// Test fallback to global treatment when flag not found
+	result = calc.Resolve("flag2", &label)
+	assert.Equal(t, "global_treatment", result.Treatment)
+	assert.Equal(t, "global_config", result.Config)
+	assert.Equal(t, "fallback - some_label", *result.Label)
+
+	// Test nil label handling
+	result = calc.Resolve("flag1", nil)
+	assert.Equal(t, "flag1_treatment", result.Treatment)
+	assert.Equal(t, "flag1_config", result.Config)
+	assert.Nil(t, result.Label)
+
+	// Test default control when no config
+	calcNoConfig := NewFallbackTreatmentCalculatorImp(nil)
+	result = calcNoConfig.Resolve("flag1", &label)
+	assert.Equal(t, "control", result.Treatment)
+	assert.Equal(t, "", result.Config)
+	assert.Equal(t, "some_label", *result.Label)
+
+	// Test global treatment when no flag-specific treatments exist
+	configGlobalOnly := &FallbackTreatmentConfig{
+		GlobalFallbackTreatment: &FallbackTreatment{
+			Treatment: "global_treatment",
+			Config:    "global_config",
+		},
+	}
+	calcGlobalOnly := NewFallbackTreatmentCalculatorImp(configGlobalOnly)
+	result = calcGlobalOnly.Resolve("any_flag", &label)
+	assert.Equal(t, "global_treatment", result.Treatment)
+	assert.Equal(t, "global_config", result.Config)
+	assert.Equal(t, "fallback - some_label", *result.Label)
+}