feat: improve compare command (#182)

Signed-off-by: Michael Beemer <beeme1mr@users.noreply.github.com>

Author: beeme1mr

docs/commands/openfeature_compare.md

@@ -15,9 +15,10 @@ openfeature compare [flags]
 ### Options
 
 ```
-  -a, --against string   Path to the target manifest file to compare against
-  -h, --help             help for compare
-  -o, --output string    Output format. Valid formats: tree, flat, json, yaml (default "tree")
+  -a, --against string       Path to the target manifest file to compare against
+  -h, --help                 help for compare
+  -i, --ignore stringArray   Field pattern to ignore during comparison (can be specified multiple times). Supports shorthand (e.g., 'description') and full paths with wildcards (e.g., 'flags.*.description', 'metadata.*')
+  -o, --output string        Output format. Valid formats: tree, flat, json, yaml (default "tree")
 ```
 
 ### Options inherited from parent commands

internal/cmd/compare.go

@@ -4,6 +4,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"reflect"
+	"sort"
 	"strings"
 
 	"github.com/open-feature/cli/internal/config"
@@ -26,6 +28,7 @@ func GetCompareCmd() *cobra.Command {
 			sourcePath := config.GetManifestPath(cmd)
 			targetPath, _ := cmd.Flags().GetString("against")
 			outputFormat, _ := cmd.Flags().GetString("output")
+			ignorePatterns, _ := cmd.Flags().GetStringArray("ignore")
 
 			// Validate flags
 			if sourcePath == "" || targetPath == "" {
@@ -49,8 +52,10 @@ func GetCompareCmd() *cobra.Command {
 				return fmt.Errorf("error loading target manifest: %w", err)
 			}
 
-			// Compare manifests
-			changes, err := manifest.Compare(sourceManifest, targetManifest)
+			// Compare manifests with ignore patterns
+			changes, err := manifest.Compare(sourceManifest, targetManifest, manifest.CompareOptions{
+				IgnorePatterns: ignorePatterns,
+			})
 			if err != nil {
 				return fmt.Errorf("error comparing manifests: %w", err)
 			}
@@ -79,6 +84,9 @@ func GetCompareCmd() *cobra.Command {
 	compareCmd.Flags().StringP("against", "a", "", "Path to the target manifest file to compare against")
 	compareCmd.Flags().StringP("output", "o", string(manifest.OutputFormatTree),
 		fmt.Sprintf("Output format. Valid formats: %s", strings.Join(manifest.GetValidOutputFormats(), ", ")))
+	compareCmd.Flags().StringArrayP("ignore", "i", []string{},
+		"Field pattern to ignore during comparison (can be specified multiple times). "+
+			"Supports shorthand (e.g., 'description') and full paths with wildcards (e.g., 'flags.*.description', 'metadata.*')")
 
 	// Mark required flags
 	_ = compareCmd.MarkFlagRequired("against")
@@ -156,26 +164,128 @@ func renderTreeDiff(changes []manifest.Change, cmd *cobra.Command) error {
 			flagName := strings.TrimPrefix(change.Path, "flags.")
 			pterm.FgYellow.Printf("  ~ %s\n", flagName)
 
-			// Marshall the values
-			oldJSON, _ := json.MarshalIndent(change.OldValue, "", "  ")
-			newJSON, _ := json.MarshalIndent(change.NewValue, "", "  ")
-
-			// Print the diff
-			fmt.Println("    Before:")
-			for _, line := range strings.Split(string(oldJSON), "\n") {
-				fmt.Printf("      %s\n", line)
-			}
-
-			fmt.Println("    After:")
-			for _, line := range strings.Split(string(newJSON), "\n") {
-				fmt.Printf("      %s\n", line)
+			// Show field-level diff
+			fieldChanges := getFieldChanges(flagName, change.OldValue, change.NewValue)
+			if len(fieldChanges) > 0 {
+				for _, fc := range fieldChanges {
+					fmt.Printf("    • %s: %s → %s\n", fc.Field, fc.OldValue, fc.NewValue)
+				}
+			} else {
+				// Fallback to full object display if we can't parse
+				oldJSON, _ := json.MarshalIndent(change.OldValue, "      ", "  ")
+				newJSON, _ := json.MarshalIndent(change.NewValue, "      ", "  ")
+				fmt.Println("    Before:")
+				fmt.Printf("      %s\n", oldJSON)
+				fmt.Println("    After:")
+				fmt.Printf("      %s\n", newJSON)
 			}
 		}
 	}
 
 	return nil
 }
 
+// fieldChange represents a change to a specific field
+type fieldChange struct {
+	Field    string
+	OldValue string
+	NewValue string
+}
+
+// getFieldChanges extracts field-level changes between two flag objects
+func getFieldChanges(flagName string, oldVal, newVal any) []fieldChange {
+	var changes []fieldChange
+
+	// Convert to maps
+	oldMap, oldOk := oldVal.(map[string]any)
+	newMap, newOk := newVal.(map[string]any)
+
+	if !oldOk || !newOk {
+		return changes // Return empty if not maps
+	}
+
+	// Get all unique field names
+	allFields := make(map[string]bool)
+	for field := range oldMap {
+		allFields[field] = true
+	}
+	for field := range newMap {
+		allFields[field] = true
+	}
+
+	// Compare each field
+	// Note: Fields are already filtered at the Compare() level, so we don't need to filter here
+	for field := range allFields {
+		oldFieldVal, oldExists := oldMap[field]
+		newFieldVal, newExists := newMap[field]
+
+		// Field was added
+		if !oldExists && newExists {
+			changes = append(changes, fieldChange{
+				Field:    field,
+				OldValue: "(not set)",
+				NewValue: formatFieldValue(newFieldVal),
+			})
+			continue
+		}
+
+		// Field was removed
+		if oldExists && !newExists {
+			changes = append(changes, fieldChange{
+				Field:    field,
+				OldValue: formatFieldValue(oldFieldVal),
+				NewValue: "(removed)",
+			})
+			continue
+		}
+
+		// Field changed
+		if !reflect.DeepEqual(oldFieldVal, newFieldVal) {
+			changes = append(changes, fieldChange{
+				Field:    field,
+				OldValue: formatFieldValue(oldFieldVal),
+				NewValue: formatFieldValue(newFieldVal),
+			})
+		}
+	}
+
+	// Sort changes by field name for consistent output
+	sort.Slice(changes, func(i, j int) bool {
+		return changes[i].Field < changes[j].Field
+	})
+
+	return changes
+}
+
+// formatFieldValue converts a value to a human-readable string for field-level diff display
+func formatFieldValue(val any) string {
+	if val == nil {
+		return "null"
+	}
+
+	switch v := val.(type) {
+	case string:
+		return fmt.Sprintf("%q", v)
+	case bool:
+		return fmt.Sprintf("%t", v)
+	case float64:
+		// Check if it's actually an integer
+		if v == float64(int64(v)) {
+			return fmt.Sprintf("%d", int64(v))
+		}
+		return fmt.Sprintf("%g", v)
+	case map[string]any, []any:
+		// For complex types, marshal to compact JSON
+		jsonBytes, err := json.Marshal(v)
+		if err != nil {
+			return fmt.Sprintf("%v", v)
+		}
+		return string(jsonBytes)
+	default:
+		return fmt.Sprintf("%v", v)
+	}
+}
+
 // renderFlatDiff renders changes in a flat format
 func renderFlatDiff(changes []manifest.Change, cmd *cobra.Command) error {
 	pterm.Info.Printf("Found %d difference(s) between manifests:\n\n", len(changes))

internal/cmd/compare_test.go

@@ -1,7 +1,10 @@
 package cmd
 
 import (
+	"bytes"
 	"fmt"
+	"io"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -21,6 +24,10 @@ func TestGetCompareCmd(t *testing.T) {
 	outputFlag := cmd.Flag("output")
 	assert.NotNil(t, outputFlag)
 	assert.Equal(t, "tree", outputFlag.DefValue)
+
+	// Verify ignore flag
+	ignoreFlag := cmd.Flag("ignore")
+	assert.NotNil(t, ignoreFlag)
 }
 
 func TestCompareManifests(t *testing.T) {
@@ -48,3 +55,109 @@ func TestCompareManifests(t *testing.T) {
 		})
 	}
 }
+
+// captureStdout captures stdout during test execution
+func captureStdout(f func()) string {
+	old := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	f()
+
+	w.Close()
+	os.Stdout = old
+
+	var buf bytes.Buffer
+	_, err := io.Copy(&buf, r)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "captureStdout: error copying output: %v\n", err)
+	}
+	return buf.String()
+}
+
+func TestCompareWithIgnoreFlag(t *testing.T) {
+	// Test that the ignore flag is properly parsed and passed to comparison
+
+	t.Run("single_ignore_pattern", func(t *testing.T) {
+		output := captureStdout(func() {
+			rootCmd := GetRootCmd()
+
+			rootCmd.SetArgs([]string{
+				"compare",
+				"--manifest", "testdata/source_manifest.json",
+				"--against", "testdata/target_manifest.json",
+				"--ignore", "description",
+			})
+
+			err := rootCmd.Execute()
+			assert.NoError(t, err, "Command should execute with single ignore pattern")
+		})
+
+		// Verify that the output doesn't contain description changes in the field-level diff
+		// The word "description" may still appear in JSON for additions/removals, which is fine
+		assert.NotContains(t, output, "• description:",
+			"Output should not show description field changes when it's ignored")
+	})
+
+	t.Run("multiple_ignore_patterns", func(t *testing.T) {
+		output := captureStdout(func() {
+			rootCmd := GetRootCmd()
+
+			rootCmd.SetArgs([]string{
+				"compare",
+				"--manifest", "testdata/source_manifest.json",
+				"--against", "testdata/target_manifest.json",
+				"--ignore", "description",
+				"--ignore", "metadata.*",
+			})
+
+			err := rootCmd.Execute()
+			assert.NoError(t, err, "Command should execute with multiple ignore patterns")
+		})
+
+		// Verify that the output doesn't contain ignored fields in the field-level diff
+		assert.NotContains(t, output, "• description:",
+			"Output should not show description field changes when it's ignored")
+		assert.NotContains(t, output, "• metadata",
+			"Output should not show metadata field changes when it's ignored")
+	})
+
+	t.Run("ignore_with_wildcard", func(t *testing.T) {
+		output := captureStdout(func() {
+			rootCmd := GetRootCmd()
+
+			rootCmd.SetArgs([]string{
+				"compare",
+				"--manifest", "testdata/source_manifest.json",
+				"--against", "testdata/target_manifest.json",
+				"--ignore", "flags.*.description",
+			})
+
+			err := rootCmd.Execute()
+			assert.NoError(t, err, "Command should execute with wildcard ignore pattern")
+		})
+
+		// Verify that the output doesn't contain description changes in the field-level diff
+		assert.NotContains(t, output, "• description:",
+			"Output should not show description field changes when using wildcard pattern 'flags.*.description'")
+	})
+
+	t.Run("without_ignore_shows_description", func(t *testing.T) {
+		output := captureStdout(func() {
+			rootCmd := GetRootCmd()
+
+			rootCmd.SetArgs([]string{
+				"compare",
+				"--manifest", "testdata/source_manifest.json",
+				"--against", "testdata/target_manifest.json",
+			})
+
+			err := rootCmd.Execute()
+			assert.NoError(t, err, "Command should execute without ignore pattern")
+		})
+
+		// Verify that the output DOES contain description field changes when not ignored
+		assert.Contains(t, output, "• description:",
+			"Output should show description field changes when it's not ignored")
+	})
+}