Honor the NO_COLOR environment variable.

junit-interface/src/main/java/munit/internal/junitinterface/Ansi.java

@@ -22,8 +22,15 @@ public class Ansi {
   private static final String LIGHT_MAGENTA = "\u001B[95m";
   private static final String LIGHT_CYAN = "\u001B[96m";
 
+  private static final boolean noColor = shouldDisableColor();
+
+  private static final boolean shouldDisableColor() {
+    String noColorEnv = System.getenv("NO_COLOR");
+    return noColorEnv != null && noColorEnv.length() > 0;
+  }
+
   public static String c(String s, String colorSequence) {
-    if (colorSequence == null) return s;
+    if (colorSequence == null || noColor) return s;
     else return colorSequence + s + NORMAL;
   }
 

munit/js-native/src/main/scala/munit/internal/junitinterface/JUnitReporter.scala

@@ -230,11 +230,11 @@ final class JUnitReporter(
     }
     val canHighlight = !PlatformCompat.isNative
     new StringBuilder()
-      .append(AnsiColors.Reset)
+      .append(AnsiColors.use(AnsiColors.Reset))
       .append(
         if (!canHighlight) ""
-        else if (highlight) AnsiColors.Bold
-        else AnsiColors.DarkGrey
+        else if (highlight) AnsiColors.use(AnsiColors.Bold)
+        else AnsiColors.use(AnsiColors.DarkGrey)
       )
       .append("    at ")
       .append(settings.decodeName(e.getClassName + '.' + e.getMethodName))
@@ -259,7 +259,7 @@ final class JUnitReporter(
         }
       )
       .append(')')
-      .append(AnsiColors.Reset)
+      .append(AnsiColors.use(AnsiColors.Reset))
       .toString()
   }
   private def formatTime(elapsedMillis: Double): String =

munit/shared/src/main/scala/munit/internal/console/AnsiColors.scala

@@ -15,8 +15,14 @@ object AnsiColors {
   val GREEN = "\u001B[32m"
   val DarkGrey = "\u001B[90m"
 
+  val noColor: Boolean =
+    Option(System.getenv("NO_COLOR")).exists(_ != "")
+
+  def use(colorSequence: String): String =
+    if (noColor) "" else colorSequence
+
   def c(s: String, colorSequence: String): String =
-    if (colorSequence == null) s
+    if (colorSequence == null || noColor) s
     else colorSequence + s + Reset
 
   def filterAnsi(s: String): String = {

munit/shared/src/main/scala/munit/internal/console/Lines.scala

@@ -44,10 +44,10 @@ class Lines extends Serializable {
           .append(format(location.line - 1))
           .append(slice(0))
           .append('\n')
-          .append(AnsiColors.Reversed)
+          .append(AnsiColors.use(AnsiColors.Reversed))
           .append(format(location.line))
           .append(slice(1))
-          .append(AnsiColors.Reset)
+          .append(AnsiColors.use(AnsiColors.Reset))
         if (slice.length >= 3)
           out
             .append('\n')

munit/shared/src/main/scala/munit/internal/difflib/Diff.scala

@@ -43,9 +43,11 @@ class Diff(val obtained: String, val expected: String) extends Serializable {
 
   private def appendDiffOnlyReport(sb: StringBuilder): Unit = {
     header("Diff", sb)
-    sb.append(
-      s" (${AnsiColors.LightRed}- obtained${AnsiColors.Reset}, ${AnsiColors.LightGreen}+ expected${AnsiColors.Reset})"
-    ).append("\n")
+    val red = AnsiColors.use(AnsiColors.LightRed)
+    val reset = AnsiColors.use(AnsiColors.Reset)
+    val green = AnsiColors.use(AnsiColors.LightGreen)
+    sb.append(s" (${red}- obtained${reset}, ${green}+ expected${reset})")
+    sb.append("\n")
     sb.append(unifiedDiff)
   }