Test special case

Closes #8644.

PiperOrigin-RevId: 253753559
diff --git a/src/test/java/com/google/devtools/build/lib/shell/ShellUtilsTest.java b/src/test/java/com/google/devtools/build/lib/shell/ShellUtilsTest.java
index baec5db..7c6e2ba 100644
--- a/src/test/java/com/google/devtools/build/lib/shell/ShellUtilsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/shell/ShellUtilsTest.java
@@ -183,5 +183,6 @@
     assertWindowsEscapeArg("\"C:\\r x\\s\\\"", "\"\\\"C:\\r x\\s\\\\\\\"\"");
     assertWindowsEscapeArg("C:\\T U\\W\\", "\"C:\\T U\\W\\\\\"");
     assertWindowsEscapeArg("\"C:\\t u\\w\\\"", "\"\\\"C:\\t u\\w\\\\\\\"\"");
+    assertWindowsEscapeArg("\"a", "\"\\\"a\"");
   }
 }