code review 4629084: govet: automate test

src/cmd/govet/govet.go

 // 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.
 
 // Govet is a simple checker for static errors in Go source code.
 // See doc.go for more information.
 package main
 
 import (
         "flag"
@@ skipping 361 matching lines @@
                 arg = args[len(call.Args)-1]
                 if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
                         if strings.HasSuffix(lit.Value, `\n"`) {
                                 f.Badf(call.Pos(), "%s call ends with newline", name)
                         }
                 }
         }
 }
 
 // This function never executes, but it serves as a simple test for the program.
-// Test with govet -printfuncs="Bad:1,Badf:1,Warn:1,Warnf:1" govet.go
+// Test with make test.
 func BadFunctionUsedInTests() {
-        fmt.Println()                      // niladic call
-        fmt.Println("%s", "hi")            // % in call to Println
-        fmt.Printf("%s", "hi", 3)          // wrong # percents
-        fmt.Printf("%s%%%d", "hi", 3)      // right # percents
-        fmt.Printf("%.*d", 3, 3)           // right # percents, with a *
-        fmt.Printf("%.*d", 3, 3, 3)        // wrong # percents, with a *
-        printf("now is the time", "buddy") // no %s
-        Printf("now is the time", "buddy") // no %s
+        fmt.Println()                      // not an error
+        fmt.Println("%s", "hi")            // ERROR "possible formatting directive in Println call"
+        fmt.Printf("%s", "hi", 3)          // ERROR "wrong number of args in Printf call"
+        fmt.Printf("%s%%%d", "hi", 3)      // correct
+        fmt.Printf("%.*d", 3, 3)           // correct
+        fmt.Printf("%.*d", 3, 3, 3)        // ERROR "wrong number of args in Printf call"
+        printf("now is the time", "buddy") // ERROR "no formatting directive"
+        Printf("now is the time", "buddy") // ERROR "no formatting directive"
+        Printf("hi")                       // ok
         f := new(File)
-        f.Warn(0, "%s", "hello", 3)  // % in call to added function
-        f.Warnf(0, "%s", "hello", 3) // wrong # %s in call to added function
+        f.Warn(0, "%s", "hello", 3)  // ERROR "possible formatting directive in Warn call"
+        f.Warnf(0, "%s", "hello", 3) // ERROR "wrong number of args in Warnf call"
 }
 
 type BadTypeUsedInTests struct {
-        X int "hello" // struct field not well-formed
+        X int "hello" // ERROR "struct field tag"
 }
 
 // printf is used by the test.
 func printf(format string, args ...interface{}) {
         panic("don't call - testing only")
 }