add test for type switches

R=rsc
DELTA=169  (169 added, 0 deleted, 0 changed)
OCL=26433
CL=26437

test/typeswitch.go

+// $G $F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+const (
+	Bool = iota;
+	Int;
+	Float;
+	String;
+	Struct;
+	Chan;
+	Array;
+	Map;
+	Func;
+	Last;
+)
+
+type S struct { a int }
+var s S = S{1234}
+
+var c = make(chan int);
+
+var a	= []int{0,1,2,3}
+
+var m = make(map[string]int)
+
+func assert(b bool, s string) {
+	if !b {
+		println(s);
+		sys.Exit(1);
+	}
+}
+
+
+func f(i int) interface{} {
+	switch i {
+	case Bool:
+		return true;
+	case Int:
+		return 7;
+	case Float:
+		return 7.4;
+	case String:
+		return "hello";
+	case Struct:
+		return s;
+	case Chan:
+		return c;
+	case Array:
+		return a;
+	case Map:
+		return m;
+	case Func:
+		return f;
+	}
+	panic("bad type number");
+}
+
+func main() {
+	// type guard style
+	for i := Bool; i < Last; i++ {
+		switch v := f(i); true {
+		case x := v.(bool):
+			assert(x == true && i == Bool, "switch 1 bool");
+		case x := v.(int):
+			assert(x == 7 && i == Int, "switch 1 int");
+		case x := v.(float):
+			assert(x == 7.4 && i == Float, "switch 1 float");
+		case x := v.(string):
+			assert(x == "hello" && i == String, "switch 1 string");
+		case x := v.(S):
+			assert(x.a == 1234 && i == Struct, "switch 1 struct");
+		case x := v.(chan int):
+			assert(x == c && i == Chan, "switch 1 chan");
+		case x := v.([]int):
+			assert(x[3] == 3 && i == Array, "switch 1 array");
+		case x := v.(map[string]int):
+			assert(x == m && i == Map, "switch 1 map");
+		case x := v.(func(i int) interface{}):
+			assert(x == f && i == Func, "switch 1 fun");
+		default:
+			assert(false, "switch 1 unknown");
+		}
+	}
+
+	// type switch style
+	for i := Bool; i < Last; i++ {
+		switch x := f(i).(type) {
+		case bool:
+			assert(x == true, "switch 2 bool");
+		case int:
+			assert(x == 7, "switch 2 int");
+		case float:
+			assert(x == 7.4, "switch 2 float");
+		case string:
+			assert(x == "hello", "switch 2 string");
+		case S:
+			assert(x.a == 1234, "switch 2 struct");
+		case chan int:
+			assert(x == c, "switch 2 chan");
+		case []int:
+			assert(x[3] == 3, "switch 2 array");
+		case map[string]int:
+			assert(x == m, "switch 2 map");
+		case func(i int) interface{}:
+			assert(x == f, "switch 2 fun");
+		default:
+			assert(false, "switch 2 unknown");
+		}
+	}
+
+	// catch-all style in various forms
+	switch {
+	case true:
+		assert(true, "switch 3 bool");
+	default:
+		assert(false, "switch 3 unknown");
+	}
+
+	switch true {
+	case true:
+		assert(true, "switch 3 bool");
+	default:
+		assert(false, "switch 3 unknown");
+	}
+
+	switch false {
+	case false:
+		assert(true, "switch 4 bool");
+	default:
+		assert(false, "switch 4 unknown");
+	}
+
+	switch true {
+	case x := f(Int).(float):
+		assert(false, "switch 5 type guard wrong type");
+	case x := f(Int).(int):
+		assert(x == 7, "switch 5 type guard");
+	default:
+		assert(false, "switch 5 unknown");
+	}
+
+	m["7"] = 7;
+	switch true {
+	case x := m["6"]:
+		assert(false, "switch 6 map reference wrong");
+	case x := m["7"]:
+		assert(x == 7, "switch 6 map reference");
+	default:
+		assert(false, "switch 6 unknown");
+	}
+
+	go func() { <-c; c <- 77; } ();
+	// guarantee the channel is ready
+	c <- 77;
+	for i := 0; i < 5; i++ {
+		sys.Gosched();
+	}
+	dummyc := make(chan int);
+	switch true {
+	case x := <-dummyc:
+		assert(false, "switch 7 chan wrong");
+	case x := <-c:
+		assert(x == 77, "switch 7 chan");
+	default:
+		assert(false, "switch 7 unknown");
+	}
+
+}