From 471e743fcaf27b8fcd8b1c3dabd2e5cb15c60ce7 Mon Sep 17 00:00:00 2001
From: Evan Wallace <evan.exe@gmail.com>
Date: Sun, 28 Mar 2021 00:37:35 -0700
Subject: [PATCH] show snapshot test diffs in color

---
 internal/bundler/bundler_test.go |  3 ++-
 internal/logger/logger.go        |  6 +++---
 internal/test/diff.go            | 31 +++++++++++++++++++++++--------
 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/internal/bundler/bundler_test.go b/internal/bundler/bundler_test.go
index 9784ddf1fb3..6db0d38d99f 100644
--- a/internal/bundler/bundler_test.go
+++ b/internal/bundler/bundler_test.go
@@ -37,7 +37,8 @@ func assertEqual(t *testing.T, a interface{}, b interface{}) {
 		stringA := fmt.Sprintf("%v", a)
 		stringB := fmt.Sprintf("%v", b)
 		if strings.Contains(stringA, "\n") {
-			t.Fatal(test.Diff(stringB, stringA))
+			color := !fs.CheckIfWindows()
+			t.Fatal(test.Diff(stringB, stringA, color))
 		} else {
 			t.Fatalf("%s != %s", a, b)
 		}
diff --git a/internal/logger/logger.go b/internal/logger/logger.go
index 3f3f33e55ac..1f749e1abf7 100644
--- a/internal/logger/logger.go
+++ b/internal/logger/logger.go
@@ -509,7 +509,7 @@ type Colors struct {
 	Yellow  string
 }
 
-var terminalColors = Colors{
+var TerminalColors = Colors{
 	Reset:     "\033[0m",
 	Bold:      "\033[1m",
 	Dim:       "\033[37m",
@@ -548,7 +548,7 @@ func PrintTextWithColor(file *os.File, useColor UseColor, callback func(Colors)
 
 	var colors Colors
 	if useColorEscapes {
-		colors = terminalColors
+		colors = TerminalColors
 	}
 	writeStringWithColor(file, callback(colors))
 }
@@ -872,7 +872,7 @@ func emptyMarginText(maxMargin int, isLast bool) string {
 func msgString(includeSource bool, terminalInfo TerminalInfo, kind MsgKind, data MsgData, maxMargin int) string {
 	var colors Colors
 	if terminalInfo.UseColorEscapes {
-		colors = terminalColors
+		colors = TerminalColors
 	}
 
 	var kindColor string
diff --git a/internal/test/diff.go b/internal/test/diff.go
index 17d28d376f9..1554a8a348b 100644
--- a/internal/test/diff.go
+++ b/internal/test/diff.go
@@ -1,32 +1,47 @@
 package test
 
 import (
+	"fmt"
 	"strings"
+
+	"github.com/evanw/esbuild/internal/logger"
 )
 
-func Diff(old string, new string) string {
-	return strings.Join(diffRec(nil, strings.Split(old, "\n"), strings.Split(new, "\n")), "\n")
+func Diff(old string, new string, color bool) string {
+	return strings.Join(diffRec(nil, strings.Split(old, "\n"), strings.Split(new, "\n"), color), "\n")
 }
 
 // This is a simple recursive line-by-line diff implementation
-func diffRec(result []string, old []string, new []string) []string {
+func diffRec(result []string, old []string, new []string, color bool) []string {
 	o, n, common := lcSubstr(old, new)
 
 	if common == 0 {
 		// Everything changed
 		for _, line := range old {
-			result = append(result, "-"+line)
+			if color {
+				result = append(result, fmt.Sprintf("%s-%s%s", logger.TerminalColors.Red, line, logger.TerminalColors.Reset))
+			} else {
+				result = append(result, "-"+line)
+			}
 		}
 		for _, line := range new {
-			result = append(result, "+"+line)
+			if color {
+				result = append(result, fmt.Sprintf("%s+%s%s", logger.TerminalColors.Green, line, logger.TerminalColors.Reset))
+			} else {
+				result = append(result, "+"+line)
+			}
 		}
 	} else {
 		// Something in the middle stayed the same
-		result = diffRec(result, old[:o], new[:n])
+		result = diffRec(result, old[:o], new[:n], color)
 		for _, line := range old[o : o+common] {
-			result = append(result, " "+line)
+			if color {
+				result = append(result, fmt.Sprintf("%s %s%s", logger.TerminalColors.Dim, line, logger.TerminalColors.Reset))
+			} else {
+				result = append(result, " "+line)
+			}
 		}
-		result = diffRec(result, old[o+common:], new[n+common:])
+		result = diffRec(result, old[o+common:], new[n+common:], color)
 	}
 
 	return result