diff --git a/test/named1.go b/test/named1.go
index 5ff6930f7d0..62b874c5cb9 100644
--- a/test/named1.go
+++ b/test/named1.go
@@ -6,6 +6,7 @@
 
 // Test that basic operations on named types are valid
 // and preserve the type.
+// Does not compile.
 
 package main
 
diff --git a/test/shift1.go b/test/shift1.go
index 393e79ee222..b33d22ff8ef 100644
--- a/test/shift1.go
+++ b/test/shift1.go
@@ -4,7 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test illegal shifts.
 // Issue 1708, illegal cases.
+// Does not compile.
 
 package p
 
diff --git a/test/shift2.go b/test/shift2.go
index cf0a45fdbfe..88ef3c40f52 100644
--- a/test/shift2.go
+++ b/test/shift2.go
@@ -4,7 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test legal shifts.
 // Issue 1708, legal cases.
+// Compiles but does not run.
 
 package p
 
diff --git a/test/sieve.go b/test/sieve.go
index 31c4ed5c05e..0cd120c548e 100644
--- a/test/sieve.go
+++ b/test/sieve.go
@@ -1,11 +1,12 @@
 // build
 
-// don't run it - goes forever
-
 // 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.
 
+// Test basic concurrency: the classic prime sieve.
+// Do not run - loops forever.
+
 package main
 
 // Send the sequence 2, 3, 4, ... to channel 'ch'.
diff --git a/test/sigchld.go b/test/sigchld.go
index e7c3d5abb48..25625a6f414 100644
--- a/test/sigchld.go
+++ b/test/sigchld.go
@@ -5,6 +5,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test that a program can survive SIGCHLD.
+
 package main
 
 import "syscall"
diff --git a/test/simassign.go b/test/simassign.go
index 349895152c5..6ba5c783e96 100644
--- a/test/simassign.go
+++ b/test/simassign.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test simultaneous assignment.
+
 package main
 
 var a, b, c, d, e, f, g, h, i int
diff --git a/test/sinit.go b/test/sinit.go
index 5cd3a4567b8..1bc28103764 100644
--- a/test/sinit.go
+++ b/test/sinit.go
@@ -4,6 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test that many initializations can be done at link time and
+// generate no executable init functions.
+
 package p
 
 // Should be no init func in the assembly.
diff --git a/test/sizeof.go b/test/sizeof.go
index 292f73ae4d1..a6abdd5c657 100644
--- a/test/sizeof.go
+++ b/test/sizeof.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test unsafe.Sizeof, unsafe.Alignof, and unsafe.Offsetof all return uintptr.
+
 package main
 
 import "unsafe"
diff --git a/test/solitaire.go b/test/solitaire.go
index 99c194f5bba..ac54cec0ac7 100644
--- a/test/solitaire.go
+++ b/test/solitaire.go
@@ -1,11 +1,13 @@
 // build
 
-// don't run it - produces too much output
-
 // Copyright 2010 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.
 
+// Test general operation by solving a peg solitaire game.
+// A version of this is in the Go playground.
+// Don't run it - produces too much output.
+
 // This program solves the (English) peg solitaire board game.
 // See also: http://en.wikipedia.org/wiki/Peg_solitaire
 
diff --git a/test/stack.go b/test/stack.go
index 2a7ce21f33a..b62febd48dd 100644
--- a/test/stack.go
+++ b/test/stack.go
@@ -4,6 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test stack splitting code.
 // Try to tickle stack splitting bugs by doing
 // go, defer, and closure calls at different stack depths.
 
diff --git a/test/string_lit.go b/test/string_lit.go
index 7f1ca35bc94..956330038ee 100644
--- a/test/string_lit.go
+++ b/test/string_lit.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test string literal syntax.
+
 package main
 
 import "os"
diff --git a/test/stringrange.go b/test/stringrange.go
index a1534c49cbe..daaba91c697 100644
--- a/test/stringrange.go
+++ b/test/stringrange.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test range over strings.
+
 package main
 
 import (
diff --git a/test/struct0.go b/test/struct0.go
index 490d3897391..e29eb30f544 100644
--- a/test/struct0.go
+++ b/test/struct0.go
@@ -4,9 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// zero length structs.
-// used to not be evaluated.
-// issue 2232.
+// Test zero length structs.
+// Used to not be evaluated.
+// Issue 2232.
 
 package main
 
diff --git a/test/switch.go b/test/switch.go
index 68bd117f0b4..09bf4341a00 100644
--- a/test/switch.go
+++ b/test/switch.go
@@ -4,8 +4,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test switch statements.
+
 package main
 
+import "os"
+
 func assert(cond bool, msg string) {
 	if !cond {
 		print("assertion fail: ", msg, "\n")
@@ -279,4 +283,13 @@ func main() {
 		assert(false, "m should not be nil")
 	default:
 	}
+
+	i := 0
+	switch x := 5; {
+		case i < x:
+			os.Exit(0)
+		case i == x:
+		case i > x:
+			os.Exit(1)
+	}
 }
diff --git a/test/switch1.go b/test/switch1.go
deleted file mode 100644
index 484a5c3afaf..00000000000
--- a/test/switch1.go
+++ /dev/null
@@ -1,20 +0,0 @@
-// run
-
-// 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
-
-import "os"
-
-func main() {
-	i := 0
-	switch x := 5; {
-		case i < x:
-			os.Exit(0)
-		case i == x:
-		case i > x:
-			os.Exit(1)
-	}
-}
diff --git a/test/switch3.go b/test/switch3.go
index 404b62e391a..dcb6fff2084 100644
--- a/test/switch3.go
+++ b/test/switch3.go
@@ -4,6 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Verify that erroneous switch statements are detected by the compiler.
+// Does not compile.
+
 package main
 
 type I interface {
diff --git a/test/test0.go b/test/test0.go
deleted file mode 100644
index ba88b1dbd4f..00000000000
--- a/test/test0.go
+++ /dev/null
@@ -1,92 +0,0 @@
-// run
-
-// 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 a_const = 0
-
-const (
-	pi    = /* the usual */ 3.14159265358979323
-	e     = 2.718281828
-	mask1 int = 1 << iota
-	mask2 = 1 << iota
-	mask3 = 1 << iota
-	mask4 = 1 << iota
-)
-
-type (
-	Empty interface{}
-	Point struct {
-		x, y int
-	}
-	Point2 Point
-)
-
-func (p *Point) Initialize(x, y int) *Point {
-	p.x, p.y = x, y
-	return p
-}
-
-func (p *Point) Distance() int {
-	return p.x*p.x + p.y*p.y
-}
-
-var (
-	x1      int
-	x2      int
-	u, v, w float32
-)
-
-func foo() {}
-
-func min(x, y int) int {
-	if x < y {
-		return x
-	}
-	return y
-}
-
-func swap(x, y int) (u, v int) {
-	u = y
-	v = x
-	return
-}
-
-func control_structs() {
-	var p *Point = new(Point).Initialize(2, 3)
-	i := p.Distance()
-	var f float32 = 0.3
-	_ = f
-	for {
-	}
-	for {
-	}
-	for j := 0; j < i; j++ {
-		if i == 0 {
-		} else {
-			i = 0
-		}
-		var x float32
-		_ = x
-	}
-foo: // a label
-	var j int
-	switch y := 0; true {
-	case i < y:
-		fallthrough
-	case i < j:
-	case i == 0, i == 1, i == j:
-		i++
-		i++
-		goto foo
-	default:
-		i = -+-+i
-		break
-	}
-}
-
-func main() {
-}
diff --git a/test/turing.go b/test/turing.go
index f5a2be2321a..acbe85b646c 100644
--- a/test/turing.go
+++ b/test/turing.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test simulating a Turing machine, sort of.
+
 package main
 
 // brainfuck
diff --git a/test/typeswitch.go b/test/typeswitch.go
index 1f864db9f74..30a4b4975fb 100644
--- a/test/typeswitch.go
+++ b/test/typeswitch.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test simple type switches, including chans, maps etc.
+
 package main
 
 import "os"
diff --git a/test/typeswitch1.go b/test/typeswitch1.go
index 8b33d39bc0f..a980ce4c070 100644
--- a/test/typeswitch1.go
+++ b/test/typeswitch1.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test simple type switches on basic types.
+
 package main
 
 import "fmt"
diff --git a/test/typeswitch2.go b/test/typeswitch2.go
index 69088e0d4f3..6c703076a6f 100644
--- a/test/typeswitch2.go
+++ b/test/typeswitch2.go
@@ -4,6 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Verify that various erroneous type switches are caught be the compiler.
+// Does not compile.
+
 package main
 
 import "io"
diff --git a/test/typeswitch3.go b/test/typeswitch3.go
index 69a2fca8b16..5475a8a6d37 100644
--- a/test/typeswitch3.go
+++ b/test/typeswitch3.go
@@ -4,6 +4,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Verify that erroneous type switches are caught be the compiler.
+// Issue 2700, among other things.
+// Does not compile.
+
 package main
 
 import (
diff --git a/test/undef.go b/test/undef.go
index 461006d2cb3..0a77e59370b 100644
--- a/test/undef.go
+++ b/test/undef.go
@@ -4,7 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Check line numbers in error messages.
+// Test line numbers in error messages.
+// Does not compile.
 
 package main
 
diff --git a/test/utf.go b/test/utf.go
index 0a3a1c0d6b4..3ac79447e63 100644
--- a/test/utf.go
+++ b/test/utf.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test UTF-8 in strings and character constants.
+
 package main
 
 import "unicode/utf8"
diff --git a/test/varerr.go b/test/varerr.go
index 4056c16d031..22aa9324f98 100644
--- a/test/varerr.go
+++ b/test/varerr.go
@@ -4,6 +4,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Verify that a couple of illegal variable declarations are caught by the compiler.
+// Does not compile.
+
 package main
 
 func main() {
diff --git a/test/varinit.go b/test/varinit.go
index 5614783e04e..84a4a1aa55c 100644
--- a/test/varinit.go
+++ b/test/varinit.go
@@ -4,6 +4,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Test var x = x + 1 works.
+
 package main
 
 func main() {