1 files changed, 73 insertions, 0 deletions
diff --git a/chapter-sccp/src/test/java/com/seaofnodes/simple/MutabilityTest.java b/chapter-sccp/src/test/java/com/seaofnodes/simple/MutabilityTest.java
new file mode 100644
index 00000000..51e31a17
--- /dev/null
+++ b/chapter-sccp/src/test/java/com/seaofnodes/simple/MutabilityTest.java
@@ -0,0 +1,73 @@
+package com.seaofnodes.simple;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+import com.seaofnodes.simple.codegen.CodeGen;
+
+public class MutabilityTest {
+    private static void ok(String src, String result) {
+        var code = new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
+        assertEquals(result,Eval2.eval(code,0));
+    }
+    private static void bad(String src) {
+        try {
+            new CodeGen(src).driver(CodeGen.Phase.TypeCheck);
+        } catch( RuntimeException expected ) {
+            String msg = expected.getMessage();
+            assertTrue("Expected a permission error, got: "+expected,
+                msg!=null && (msg.contains("final") || msg.contains("not of declared type") || msg.contains("Cannot store") || msg.contains("Argument #")));
+            return;
+        }
+        fail("Accepted forbidden write: "+src);
+    }
+
+    @Test public void testIndependentBindingsAndViews() {
+        ok("struct P { int x; }; !P ~p=new P; p.x=7; return p.x;", "7");
+        ok("struct P { int x; }; ~P !p=new P{x=3;}; p=new P{x=7;}; return p.x;", "7");
+        bad("struct P { int x; }; !P ~p=new P; p=new P; return 0;");
+        bad("struct P { int x; }; ~P !p=new P; p.x=7; return 0;");
+        bad("int ~x=3; x=7; return x;");
+        ok("int !x=3; x=7; return x;", "7");
+    }
+
+    @Test public void testDeepViewAndAliases() {
+        ok("struct P { int x; }; !P ~p=new P; ~P ~r=p; p.x=7; return r.x;", "7");
+        bad("struct P { int x; }; struct Box { !P p; }; !P q=new P; Box b=new Box{p=q;}; b.p.x=7; return 0;");
+        bad("struct P { int x; }; P p=new P; !P q=p; q.x=7; return 0;");
+        bad("struct P { P? next; int x; }; !P p=new P{next=new P;}; p.next.x=7; return 0;");
+        bad("struct P { !P? next; int x; }; P p=new P{next=new P;}; p.next.x=7; return 0;");
+    }
+
+    @Test public void testInferencePreservesAccess() {
+        ok("struct P { int x; }; val p=new P; p.x=7; return p.x;", "7");
+        bad("struct P { int x; }; val p=new P; p=new P; return 0;");
+        bad("struct P { int x; }; P p=new P; var q=p; q.x=7; return 0;");
+    }
+
+    @Test public void testParameterPermissions() {
+        ok("struct P { int x; }; val f={ !P p -> p.x=7; return p.x; }; return f(new P);", "7");
+        ok("val f={ int ~x -> return x; }; return f(7);", "7");
+        bad("val f={ int ~x -> x=7; return x; }; return f(3);");
+        bad("struct P { int x; }; val f={ P p -> p.x=7; return p.x; }; return f(new P);");
+        bad("struct P { int x; }; val f={ !P p -> p.x=7; return p.x; }; P p=new P; return f(p);");
+        bad("struct P { int x; }; val f={ P?[] a -> return a#; }; !P?[] a=new !P?[1]; return f(a);");
+    }
+
+    @Test public void testConstructorScope() {
+        ok("struct P { int ~x; }; P p=new P{if(arg) x=3; else x=7;}; return p.x;", "7");
+        bad("int ~outer=1; struct P { int x; }; P p=new P{outer=7;}; return outer;");
+        bad("struct P { int x; }; P p=new P{int ~local=1; local=7;}; return p.x;");
+    }
+
+    @Test public void testArrayLayers() {
+        bad("struct P { int x; }; !P?[] rw=new !P?[1]; P?[] ro=rw; rw[0]=new P; ro[0].x=7; return 0;");
+        ok("u8[] a=new u8[2]; a[0]=7; return a[0];", "7");
+        ok("struct P { int x; }; P?[] a=new P?[1]; a[0]=new P{x=7;}; return a[0].x;", "7");
+        bad("struct P { int x; }; P?[] a=new P?[1]; a[0]=new P; a[0].x=7; return 0;");
+        ok("struct P { int x; }; !P?[] a=new !P?[1]; a[0]=new P; a[0].x=7; return a[0].x;", "7");
+        bad("u8[~] a=new u8[1]; a[0]=7; return 0;");
+        ok("u8[~]?[] rows=new u8[~]?[1]; rows[0]=new u8[1]; return rows#;", "1");
+        bad("u8[~]?[] rows=new u8[~]?[1]; rows[0]=new u8[1]; rows[0][0]=7; return 0;");
+        bad("u8[]?[~] rows=new u8[]?[1]; rows[0]=new u8[1]; return 0;");
+    }
+}