Fix race condition in Theme.Tips method when called concurrently (#109)

* Initial plan
* Fix race condition in Theme.Tips method and add test
* Fix unit test error in Theme.Tips method - maintain original styling behavior

Author: Copilot

issues_test.go

@@ -1,8 +1,10 @@
 package color_test
 
 import (
+	"bytes"
 	"fmt"
 	"strings"
+	"sync"
 	"testing"
 
 	"github.com/gookit/color"
@@ -49,3 +51,64 @@ foo <bg=lightGreen;fg=black>two</> four
 	color.Print(test2)
 	color.Print(test3)
 }
+
+// https://github.com/gookit/color/issues/95
+func TestIssues_95(t *testing.T) {
+	// Test for race condition in Theme.Tips when called concurrently
+	// We use a thread-safe buffer to avoid low-level I/O races
+	// and focus on testing the application-level race condition
+	buf := &safeBuffer{Buffer: &bytes.Buffer{}}
+	color.SetOutput(buf)
+	defer color.ResetOutput()
+
+	const numGoroutines = 20
+	var wg sync.WaitGroup
+	wg.Add(numGoroutines * 2)
+
+	// Start multiple goroutines calling Tips concurrently
+	for i := 0; i < numGoroutines; i++ {
+		go func(id int) {
+			defer wg.Done()
+			color.Warn.Tips("warning message %d", id)
+		}(i)
+
+		go func(id int) {
+			defer wg.Done()
+			color.Error.Tips("error message %d", id)
+		}(i)
+	}
+
+	wg.Wait()
+	output := buf.String()
+
+	// Clean the output of ANSI codes to check logical structure
+	cleanOutput := color.ClearCode(output)
+	lines := strings.Split(strings.TrimSpace(cleanOutput), "\n")
+	
+	// Verify that each line is properly formatted (without ANSI codes)
+	for i, line := range lines {
+		if line == "" {
+			continue
+		}
+		// Each line should start with either "WARNING:" or "ERROR:"
+		if !strings.HasPrefix(line, "WARNING:") && !strings.HasPrefix(line, "ERROR:") {
+			t.Errorf("Line %d is malformed due to race condition: %q", i, line)
+		}
+		// Should not contain both prefixes (indicating interleaved output)
+		if strings.Contains(line, "WARNING:") && strings.Contains(line, "ERROR:") {
+			t.Errorf("Line %d contains interleaved output: %q", i, line)
+		}
+	}
+}
+
+// Thread-safe buffer for testing
+type safeBuffer struct {
+	*bytes.Buffer
+	mu sync.Mutex
+}
+
+func (sb *safeBuffer) Write(p []byte) (n int, err error) {
+	sb.mu.Lock()
+	defer sb.mu.Unlock()
+	return sb.Buffer.Write(p)
+}

style.go

@@ -122,9 +122,11 @@ func (t *Theme) Save() {
 
 // Tips use name as title, only apply style for name
 func (t *Theme) Tips(format string, a ...any) {
-	// only apply style for name
-	t.Print(strings.ToUpper(t.Name) + ": ")
-	Printf(format+"\n", a...)
+	// Format the message part first
+	message := fmt.Sprintf(format, a...)
+	// Create styled title and combine with unstyled message in a single print operation to avoid race conditions
+	styledTitle := t.Style.Render(strings.ToUpper(t.Name) + ": ")
+	Printf("%s%s\n", styledTitle, message)
 }
 
 // Prompt use name as title, and apply style for message