feat: Add reason, variant to flagsmith eval output (#74)

Author: khvn26

go.mod

@@ -3,7 +3,7 @@ module github.com/Flagsmith/flagsmith-cli/v2
 go 1.26
 
 require (
-	github.com/Flagsmith/flagsmith-go-client/v5 v5.1.0
+	github.com/Flagsmith/flagsmith-go-client/v5 v5.2.0
 	github.com/blang/semver/v4 v4.0.0
 	github.com/charmbracelet/huh v1.0.0
 	github.com/fatih/color v1.19.0

go.sum

@@ -1,5 +1,5 @@
-github.com/Flagsmith/flagsmith-go-client/v5 v5.1.0 h1:/1KMxWHfzo8I7FnZ0mnMw+ICM4HVZvCEYTJ4idM2VEU=
-github.com/Flagsmith/flagsmith-go-client/v5 v5.1.0/go.mod h1:CjTs0XAIJXG+08lf4h51W9cjvrNaK92TLVYtjPrnI3w=
+github.com/Flagsmith/flagsmith-go-client/v5 v5.2.0 h1:Mqs3nEceWQixRcnIdqnju1Kqo5HvTlhcR9HTdiOsjc4=
+github.com/Flagsmith/flagsmith-go-client/v5 v5.2.0/go.mod h1:CjTs0XAIJXG+08lf4h51W9cjvrNaK92TLVYtjPrnI3w=
 github.com/MakeNowJust/heredoc v1.0.0 h1:cXCdzVdstXyiTqTvfqk9SDHpKNjxuom+DOlyEeQ4pzQ=
 github.com/MakeNowJust/heredoc v1.0.0/go.mod h1:mG5amYoWBHf8vpLOuehzbGGw0EHxpZZ6lCpQ4fNJ8LE=
 github.com/atotto/clipboard v0.1.4 h1:EH0zSVneZPSuFR11BlR9YppQTVDbh5+16AmcJi4g1z4=

internal/cmd/cmd_test.go

@@ -6938,7 +6938,6 @@ func TestEvaluate(t *testing.T) {
 		if items["value"] != float64(25) || items["enabled"] != false {
 			t.Errorf("flag = %+v, want the resolved value", items)
 		}
-		// Omitted until the SDK API returns them: absent, never faked.
 		for _, absent := range []string{"reason", "variant"} {
 			if _, ok := items[absent]; ok {
 				t.Errorf("flag = %+v, want %q omitted rather than invented", items, absent)
@@ -6949,6 +6948,86 @@ func TestEvaluate(t *testing.T) {
 		}
 	})
 
+	t.Run("json carries the reason and variant the SDK API returned", func(t *testing.T) {
+		// Given
+		f := evalEnv(t)
+		flags := sdkFlagsFrom(defaultFeatures())
+		flags[0]["reason"] = "DEFAULT"
+		flags[1]["reason"] = "SPLIT; weight=30"
+		flags[1]["variant"] = "treatment"
+		f.sdkEnvFlags["WqXhZk8sVY3dGgTqZ9pJmN"] = flags
+
+		// When
+		out, err := run("", "evaluate", "--json")
+
+		// Then
+		if err != nil {
+			t.Fatalf("evaluate --json: %v\noutput: %s", err, out)
+		}
+		resolved, _ := evalDoc(t, out)["flags"].(map[string]any)
+		items, _ := resolved["max_items"].(map[string]any)
+		if items["reason"] != "SPLIT; weight=30" || items["variant"] != "treatment" {
+			t.Errorf("flag = %+v, want the reason and variant it resolved by", items)
+		}
+		// A standard feature has no variant to report; the schema calls that null,
+		// and an EvaluationResult that is already a subset omits it.
+		banner, _ := resolved["onboarding_banner"].(map[string]any)
+		if banner["reason"] != "DEFAULT" {
+			t.Errorf("flag = %+v, want the reason it resolved by", banner)
+		}
+		if _, ok := banner["variant"]; ok {
+			t.Errorf("flag = %+v, want no variant where none applied", banner)
+		}
+	})
+
+	t.Run("the table adds VARIANT when SDK API returns a variant", func(t *testing.T) {
+		// Given
+		f := evalEnv(t)
+		flags := sdkFlagsFrom(defaultFeatures())
+		flags[0]["reason"] = "DEFAULT"
+		flags[1]["reason"] = "TARGETING_MATCH; segment=power users"
+		flags[1]["variant"] = "treatment"
+		f.sdkEnvFlags["WqXhZk8sVY3dGgTqZ9pJmN"] = flags
+
+		// When
+		out, err := run("", "evaluate")
+
+		// Then
+		if err != nil {
+			t.Fatalf("evaluate: %v\noutput: %s", err, out)
+		}
+		for _, want := range []string{
+			"VARIANT", "REASON",
+			"TARGETING_MATCH; segment=power users", "treatment", "DEFAULT",
+		} {
+			if !strings.Contains(out, want) {
+				t.Errorf("output = %q, want it to contain %q", out, want)
+			}
+		}
+	})
+
+	t.Run("the table drops the columns an SDK API left empty", func(t *testing.T) {
+		// Given
+		f := evalEnv(t)
+		flags := sdkFlagsFrom(defaultFeatures())
+		flags[0]["reason"], flags[1]["reason"] = "DEFAULT", "DEFAULT"
+		f.sdkEnvFlags["WqXhZk8sVY3dGgTqZ9pJmN"] = flags
+
+		// When
+		out, err := run("", "evaluate")
+
+		// Then
+		if !strings.Contains(out, "REASON") {
+			t.Errorf("output = %q, want the reason column", out)
+		}
+		if strings.Contains(out, "VARIANT") {
+			t.Errorf("output = %q, want no variant column where nothing was bucketed", out)
+		}
+		if err != nil {
+			t.Fatalf("evaluate: %v\noutput: %s", err, out)
+		}
+	})
+
 	t.Run("--js is the frontend SDK's hydration state", func(t *testing.T) {
 		// Given
 		f := evalEnv(t)
@@ -7172,6 +7251,32 @@ func TestEvaluate(t *testing.T) {
 		if strings.Contains(out, "onboarding_banner") {
 			t.Errorf("output = %q, want only the named feature", out)
 		}
+		for _, absent := range []string{"Reason", "Variant"} {
+			if strings.Contains(out, absent) {
+				t.Errorf("output = %q, want no %q the SDK API never reported", out, absent)
+			}
+		}
+	})
+
+	t.Run("a single feature's detail view says why it resolved", func(t *testing.T) {
+		// Given
+		f := evalEnv(t)
+		flags := sdkFlagsFrom(defaultFeatures())
+		flags[1]["reason"], flags[1]["variant"] = "SPLIT; weight=30", "treatment"
+		f.sdkEnvFlags["WqXhZk8sVY3dGgTqZ9pJmN"] = flags
+
+		// When
+		out, err := run("", "evaluate", "max_items")
+
+		// Then
+		if err != nil {
+			t.Fatalf("evaluate max_items: %v\noutput: %s", err, out)
+		}
+		for _, want := range []string{"Variant", "treatment", "Reason", "SPLIT; weight=30"} {
+			if !strings.Contains(out, want) {
+				t.Errorf("output = %q, want %q", out, want)
+			}
+		}
 	})
 
 	t.Run("an unknown feature errors with a hint", func(t *testing.T) {
@@ -7451,6 +7556,26 @@ func TestEvaluateIdentity(t *testing.T) {
 		}
 	})
 
+	t.Run("an identity's variant and reason survive the identify call", func(t *testing.T) {
+		// Given
+		f := evalEnv(t)
+		flags := overridden()
+		flags[1]["reason"], flags[1]["variant"] = "SPLIT; weight=50", "treatment"
+		f.sdkIdentityFlags["user-123"] = flags
+
+		// When
+		out, err := run("", "evaluate", "max_items", "--identity", "user-123", "--json")
+
+		// Then
+		if err != nil {
+			t.Fatalf("evaluate --identity --json: %v\noutput: %s", err, out)
+		}
+		doc := evalDoc(t, out)
+		if doc["reason"] != "SPLIT; weight=50" || doc["variant"] != "treatment" {
+			t.Errorf("doc = %+v, want the identity's reason and variant", doc)
+		}
+	})
+
 	// The flag commands name this --identifier; eval names it --identity. Both
 	// spellings work here, so nobody has to remember which command uses which.
 	for _, spelling := range []string{"--identity", "--identifier", "-i"} {

internal/cmd/evaluate.go

@@ -23,10 +23,18 @@ type evalView struct {
 	Feature string
 	Enabled bool
 	Value   any
+	Reason  string
+	Variant string
 }
 
 func newEvalView(f flagsmith.Flag) evalView {
-	return evalView{Feature: f.FeatureName, Enabled: f.Enabled, Value: f.Value}
+	return evalView{
+		Feature: f.FeatureName,
+		Enabled: f.Enabled,
+		Value:   f.Value,
+		Reason:  f.Reason,
+		Variant: f.Variant,
+	}
 }
 
 const evaluationResultSchema = "https://raw.githubusercontent.com/Flagsmith/flagsmith/main/sdk/evaluation-result.json"
@@ -44,10 +52,18 @@ type evalFlag struct {
 	Name    string `json:"name"`
 	Enabled bool   `json:"enabled"`
 	Value   any    `json:"value"`
+	Reason  string `json:"reason,omitempty"`
+	Variant string `json:"variant,omitempty"`
 }
 
 func newEvalFlag(v evalView) evalFlag {
-	return evalFlag{Name: v.Feature, Enabled: v.Enabled, Value: v.Value}
+	return evalFlag{
+		Name:    v.Feature,
+		Enabled: v.Enabled,
+		Value:   v.Value,
+		Reason:  v.Reason,
+		Variant: v.Variant,
+	}
 }
 
 func newEvalResult(views []evalView) evalResult {
@@ -190,26 +206,51 @@ func renderEvaluation(cmd *cobra.Command, sdkURL string, views []evalView, singl
 				"Warning: no flags to hydrate from — an SDK given this state will wait for a fetch")
 		}
 	}
+	var anyReason, anyVariant bool
+	for _, v := range views {
+		anyReason = anyReason || v.Reason != ""
+		anyVariant = anyVariant || v.Variant != ""
+	}
 	opts := outputOpts()
 	opts.JSON = opts.JSON || evalJSFlag
 	return output.Render(cmd.OutOrStdout(), doc, opts, func(w io.Writer) error {
 		if single {
 			v := views[0]
-			return output.Detail(w, []output.Field{
+			fields := []output.Field{
 				{Label: "Feature", Value: v.Feature},
 				{Label: "Enabled", Value: boolState(v.Enabled)},
 				{Label: "Value", Value: valueDisplay(v.Value)},
-			})
+			}
+			if v.Variant != "" {
+				fields = append(fields, output.Field{Label: "Variant", Value: v.Variant})
+			}
+			if v.Reason != "" {
+				fields = append(fields, output.Field{Label: "Reason", Value: v.Reason})
+			}
+			return output.Detail(w, fields)
 		}
 		if len(views) == 0 {
 			fmt.Fprintln(w, "No flags.")
 			return nil
 		}
+		headers := []string{"FEATURE", "ENABLED", "VALUE"}
+		if anyVariant {
+			headers = append(headers, "VARIANT")
+		}
+		if anyReason {
+			headers = append(headers, "REASON")
+		}
 		rows := make([][]string, len(views))
 		for i, v := range views {
 			rows[i] = []string{v.Feature, boolState(v.Enabled), truncateValue(valueDisplay(v.Value))}
+			if anyVariant {
+				rows[i] = append(rows[i], v.Variant)
+			}
+			if anyReason {
+				rows[i] = append(rows[i], v.Reason)
+			}
 		}
-		if err := output.Table(w, []string{"FEATURE", "ENABLED", "VALUE"}, rows); err != nil {
+		if err := output.Table(w, headers, rows); err != nil {
 			return err
 		}
 		fmt.Fprintf(w, "\n%d %s\n", len(views), plural(len(views), "flag", "flags"))