fix #423 : Add helper function and some documentation to parse shorthand go test flags.

README.md

@@ -284,6 +284,33 @@ func main() {
 }
 ```
 
+### Using pflag with go test
+`pflag` does not parse the shorthand versions of go test's built-in flags (i.e., those starting with `-test.`).
+For more context, see issues [#63](https://github.com/spf13/pflag/issues/63) and [#238](https://github.com/spf13/pflag/issues/238) for more details.
+
+For example, if you use pflag in your `TestMain` function and call `pflag.Parse()` after defining your custom flags, running a test like this:
+```bash
+go test /your/tests -run ^YourTest -v --your-test-pflags
+```
+will result in the `-v` flag being ignored. This happens because of the way pflag handles flag parsing, skipping over go test's built-in shorthand flags.
+To work around this, you can use the `ParseSkippedFlags` function, which ensures that go test's flags are parsed separately using the standard flag package.
+
+**Example**: You want to parse go test flags that are otherwise ignore by `pflag.Parse()`
+```go
+import (
+	goflag "flag"
+	flag "github.com/spf13/pflag"
+)
+
+var ip *int = flag.Int("flagname", 1234, "help message for flagname")
+
+func main() {
+	flag.CommandLine.AddGoFlagSet(goflag.CommandLine)
+    flag.ParseSkippedFlags(os.Args[1:], goflag.CommandLine)
+	flag.Parse()
+}
+```
+
 ## More info
 
 You can see the full reference documentation of the pflag package

flag.go

@@ -27,23 +27,32 @@ unaffected.
 Define flags using flag.String(), Bool(), Int(), etc.
 
 This declares an integer flag, -flagname, stored in the pointer ip, with type *int.
+
 	var ip = flag.Int("flagname", 1234, "help message for flagname")
+
 If you like, you can bind the flag to a variable using the Var() functions.
+
 	var flagvar int
 	func init() {
 		flag.IntVar(&flagvar, "flagname", 1234, "help message for flagname")
 	}
+
 Or you can create custom flags that satisfy the Value interface (with
 pointer receivers) and couple them to flag parsing by
+
 	flag.Var(&flagVal, "name", "help message for flagname")
+
 For such flags, the default value is just the initial value of the variable.
 
 After all flags are defined, call
+
 	flag.Parse()
+
 to parse the command line into the defined flags.
 
 Flags may then be used directly. If you're using the flags themselves,
 they are all pointers; if you bind to variables, they're values.
+
 	fmt.Println("ip has value ", *ip)
 	fmt.Println("flagvar has value ", flagvar)
 
@@ -54,22 +63,26 @@ The arguments are indexed from 0 through flag.NArg()-1.
 The pflag package also defines some new functions that are not in flag,
 that give one-letter shorthands for flags. You can use these by appending
 'P' to the name of any function that defines a flag.
+
 	var ip = flag.IntP("flagname", "f", 1234, "help message")
 	var flagvar bool
 	func init() {
 		flag.BoolVarP(&flagvar, "boolname", "b", true, "help message")
 	}
 	flag.VarP(&flagval, "varname", "v", "help message")
+
 Shorthand letters can be used with single dashes on the command line.
 Boolean shorthand flags can be combined with other shorthand flags.
 
 Command line flag syntax:
+
 	--flag    // boolean flags only
 	--flag=x
 
 Unlike the flag package, a single dash before an option means something
 different than a double dash. Single dashes signify a series of shorthand
 letters for flags. All but the last shorthand letter must be boolean flags.
+
 	// boolean flags
 	-f
 	-abc
@@ -934,9 +947,9 @@ func (f *FlagSet) usage() {
 	}
 }
 
-//--unknown (args will be empty)
-//--unknown --next-flag ... (args will be --next-flag ...)
-//--unknown arg ... (args will be arg ...)
+// --unknown (args will be empty)
+// --unknown --next-flag ... (args will be --next-flag ...)
+// --unknown arg ... (args will be arg ...)
 func stripUnknownFlagValue(args []string) []string {
 	if len(args) == 0 {
 		//--unknown
@@ -1014,7 +1027,7 @@ func (f *FlagSet) parseLongArg(s string, args []string, fn parseFunc) (a []strin
 func (f *FlagSet) parseSingleShortArg(shorthands string, args []string, fn parseFunc) (outShorts string, outArgs []string, err error) {
 	outArgs = args
 
-	if strings.HasPrefix(shorthands, "test.") {
+	if isGotestShorthandFlag(shorthands) {
 		return
 	}
 

golangflag.go

@@ -10,6 +10,15 @@ import (
 	"strings"
 )
 
+// go test flags prefixes
+func isGotestFlag(flag string) bool {
+	return strings.HasPrefix(flag, "-test.")
+}
+
+func isGotestShorthandFlag(flag string) bool {
+	return strings.HasPrefix(flag, "test.")
+}
+
 // flagValueWrapper implements pflag.Value around a flag.Value.  The main
 // difference here is the addition of the Type method that returns a string
 // name of the type.  As this is generally unknown, we approximate that with
@@ -103,3 +112,16 @@ func (f *FlagSet) AddGoFlagSet(newSet *goflag.FlagSet) {
 	}
 	f.addedGoFlagSets = append(f.addedGoFlagSets, newSet)
 }
+
+// ParseSkippedFlags explicitly Parses go test flags (i.e. the one starting with '-test.') with goflag.Parse(),
+// since by default those are skipped by pflag.Parse().
+// Typical usage example: `ParseGoTestFlags(os.Args[1:], goflag.CommandLine)`
+func ParseSkippedFlags(osArgs []string, goFlagSet *goflag.FlagSet) error {
+	var skippedFlags []string
+	for _, f := range osArgs {
+		if isGotestFlag(f) {
+			skippedFlags = append(skippedFlags, f)
+		}
+	}
+	return goFlagSet.Parse(skippedFlags)
+}

golangflag_test.go

@@ -12,11 +12,14 @@ import (
 func TestGoflags(t *testing.T) {
 	goflag.String("stringFlag", "stringFlag", "stringFlag")
 	goflag.Bool("boolFlag", false, "boolFlag")
+	var testxxxValue string
+	goflag.StringVar(&testxxxValue, "test.xxx", "test.xxx", "it is a test flag")
 
 	f := NewFlagSet("test", ContinueOnError)
 
 	f.AddGoFlagSet(goflag.CommandLine)
-	err := f.Parse([]string{"--stringFlag=bob", "--boolFlag"})
+	args := []string{"--stringFlag=bob", "--boolFlag", "-test.xxx=testvalue"}
+	err := f.Parse(args)
 	if err != nil {
 		t.Fatal("expected no error; get", err)
 	}
@@ -40,6 +43,17 @@ func TestGoflags(t *testing.T) {
 		t.Fatal("f.Parsed() return false after f.Parse() called")
 	}
 
+	if testxxxValue != "test.xxx" {
+		t.Fatalf("expected testxxxValue to be test.xxx but got %v", testxxxValue)
+	}
+	err = ParseSkippedFlags(args, goflag.CommandLine)
+	if err != nil {
+		t.Fatal("expected no error; ParseSkippedFlags", err)
+	}
+	if testxxxValue != "testvalue" {
+		t.Fatalf("expected testxxxValue to be testvalue but got %v", testxxxValue)
+	}
+
 	// in fact it is useless. because `go test` called flag.Parse()
 	if !goflag.CommandLine.Parsed() {
 		t.Fatal("goflag.CommandLine.Parsed() return false after f.Parse() called")