Added regression test for antlr/antlr4#2709

runtime-testsuite/test/org/antlr/v4/test/runtime/descriptors/LexerExecDescriptors.java

@@ -1057,4 +1057,33 @@ public class LexerExecDescriptors {
 			return new Pair<>(grammarName, grammar);
 		}
 	}
+
+	/**
+	 * This is a regression test for antlr/antlr4#2709 "PHP target generates
+	 * invalid output when $ is used as part of the literal in lexer rule"
+	 * https://github.com/antlr/antlr4/issues/2709
+	 */
+	public static class EscapeTargetStringLiteral extends BaseLexerTestDescriptor {
+		/**
+		[@0,0:-1='<EOF>',<-1>,1:0]
+		 */
+		@CommentHasStringValue
+		public String output;
+
+		public String errors = null;
+		public String startRule = "";
+		public String grammarName = "L";
+
+		/**
+		 lexer grammar L;
+		 ACTION_WITH_DOLLAR: '$ACTION';
+		 */
+		@CommentHasStringValue
+		public String grammar;
+
+		@Override
+		public boolean ignore(String targetName) {
+			return !targetName.equals("PHP");
+		}
+	}
 }