3 files changed, 135 insertions, 1 deletions
diff --git a/src/test/java/com/seaofnodes/simple/Chapter01Test.java b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
index 311ca23b..3d568337 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter01Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
@@ -14,7 +14,7 @@ public class Chapter01Test {
         ReturnNode ret = parser.parse();
         StartNode start = Parser.START;
 
-        assertEquals(start, ret.ctrl());
+        assertTrue(ret.ctrl() instanceof ProjNode);
         Node expr = ret.expr();
         if( expr instanceof ConstantNode con ) {
             assertEquals(start,con.in(0));
diff --git a/src/test/java/com/seaofnodes/simple/Chapter03Test.java b/src/test/java/com/seaofnodes/simple/Chapter03Test.java
index 3b8b3449..fc8e97b6 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter03Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter03Test.java
@@ -1,6 +1,7 @@
 package com.seaofnodes.simple;
 
 import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
diff --git a/src/test/java/com/seaofnodes/simple/Chapter04Test.java b/src/test/java/com/seaofnodes/simple/Chapter04Test.java
new file mode 100644
index 00000000..faae0aee
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/Chapter04Test.java
@@ -0,0 +1,133 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class Chapter04Test {
+
+    @Test
+    public void testPeephole() {
+        Parser parser = new Parser("return 1+arg+2; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (arg+3);", ret.print());
+    }
+
+    @Test
+    public void testPeephole2() {
+        Parser parser = new Parser("return (1+arg)+2;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (arg+3);", ret.print());
+    }
+
+    @Test
+    public void testAdd0() {
+        Parser parser = new Parser("return 0+arg;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return arg;", ret.print());
+    }
+
+    @Test
+    public void testAddAddMul() {
+        Parser parser = new Parser("return arg+0+arg;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (arg*2);", ret.print());
+    }
+
+    @Test
+    public void testPeephole3() {
+        Parser parser = new Parser("return 1+arg+2+arg+3; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return ((arg*2)+6);", ret.print());
+    }
+
+    @Test
+    public void testMul1() {
+        Parser parser = new Parser("return 1*arg;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return arg;", ret.print());
+    }
+
+    @Test
+    public void testVarArg() {
+        Parser parser = new Parser("return arg; #showGraph;", TypeInteger.BOT);
+        ReturnNode ret = parser.parse();
+        assertTrue(ret.in(0) instanceof ProjNode);
+        assertTrue(ret.in(1) instanceof ProjNode);
+    }
+
+    @Test
+    public void testConstantArg() {
+        Parser parser = new Parser("return arg; #showGraph;", TypeInteger.constant(2));
+        ReturnNode ret = parser.parse();
+        assertEquals("return 2;", ret.print());
+    }
+
+    @Test
+    public void testCompEq() {
+        Parser parser = new Parser("return 3==3; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return 1;", ret.print());
+    }
+
+    @Test
+    public void testCompEq2() {
+        Parser parser = new Parser("return 3==4; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return 0;", ret.print());
+    }
+
+    @Test
+    public void testCompNEq() {
+        Parser parser = new Parser("return 3!=3; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return 0;", ret.print());
+    }
+
+    @Test
+    public void testCompNEq2() {
+        Parser parser = new Parser("return 3!=4; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return 1;", ret.print());
+    }
+
+    @Test
+    public void testBug1() {
+        Parser parser = new Parser("int a=arg+1; int b=a; b=1; return a+2; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (arg+3);", ret.print());
+    }
+
+    @Test
+    public void testBug2() {
+        Parser parser = new Parser("int a=arg+1; a=a; return a; #showGraph;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (arg+1);", ret.print());
+    }
+
+    @Test
+    public void testBug3() {
+        try {
+            new Parser("inta=1; return a;").parse();
+            fail();
+        } catch( RuntimeException e ) {
+            assertEquals("Undefined name 'inta'",e.getMessage());
+        }
+    }
+
+    @Test
+    public void testBug4() {
+        Parser parser = new Parser("return -arg;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (-arg);", ret.print());
+    }
+
+    @Test
+    public void testBug5() {
+        Parser parser = new Parser("return arg--2;");
+        ReturnNode ret = parser.parse();
+        assertEquals("return (arg--2);", ret.print());
+    }
+}