1 files changed, 28 insertions, 0 deletions
diff --git a/chapter21/src/test/java/com/seaofnodes/simple/Chapter04Test.java b/chapter21/src/test/java/com/seaofnodes/simple/Chapter04Test.java
index c6199193..e5a16680 100644
--- a/chapter21/src/test/java/com/seaofnodes/simple/Chapter04Test.java
+++ b/chapter21/src/test/java/com/seaofnodes/simple/Chapter04Test.java
@@ -53,6 +53,34 @@ public class Chapter04Test {
     }
 
     @Test
+    public void testSub0() {
+        CodeGen code = new CodeGen("return arg-0;");
+        code.parse();
+        assertEquals("return arg;", code.print());
+    }
+
+    @Test
+    public void test0Sub() {
+        CodeGen code = new CodeGen("return 0-arg;");
+        code.parse();
+        assertEquals("return (-arg);", code.print());
+    }
+
+    @Test
+    public void testSubNeg() {
+        CodeGen code = new CodeGen("return 3--arg;");
+        code.parse();
+        assertEquals("return (arg+3);", code.print());
+    }
+
+    @Test
+    public void testNegSub() {
+        CodeGen code = new CodeGen("return -arg-3;");
+        code.parse();
+        assertEquals("return (-(arg+3));", code.print());
+    }
+
+    @Test
     public void testVarArg() {
         CodeGen code = new CodeGen("return arg; ");
         code.parse();