pkg/tool: add package

Package tool contains various helper utilitites useful for implementation of command line tools.
Currently it contains Fail/Failf functions that we commonly use
and new support for optional command line flags.

1 files changed, 62 insertions, 0 deletions

diff --git a/pkg/tool/flags_test.go b/pkg/tool/flags_test.go
new file mode 100644
index 000000000..6d52a4780
--- /dev/null
+++ b/pkg/tool/flags_test.go
@@ -0,0 +1,62 @@
+// Copyright 2020 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package tool
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestParseFlags(t *testing.T) {
+	type Values struct {
+		Foo bool
+		Bar int
+		Baz string
+	}
+	type Test struct {
+		args string
+		vals *Values
+	}
+	tests := []Test{
+		{"", &Values{false, 1, "baz"}},
+		{"-foo -bar=2", &Values{true, 2, "baz"}},
+		{"-foo -bar=2 -qux", nil},
+		{"-foo -bar=2 " + OptionalFlags(Flag{"qux", ""}), &Values{true, 2, "baz"}},
+	}
+	for i, test := range tests {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			vals := new(Values)
+			flags := flag.NewFlagSet("", flag.ContinueOnError)
+			flags.SetOutput(ioutil.Discard)
+			flags.BoolVar(&vals.Foo, "foo", false, "")
+			flags.IntVar(&vals.Bar, "bar", 1, "")
+			flags.StringVar(&vals.Baz, "baz", "baz", "")
+			args := append(strings.Split(test.args, " "), "arg0", "arg1")
+			if args[0] == "" {
+				args = args[1:]
+			}
+			err := parseFlags(flags, args)
+			if test.vals == nil {
+				if err == nil {
+					t.Fatalf("parsing did not fail")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("parsing failed: %v", err)
+			}
+			if diff := cmp.Diff(test.vals, vals); diff != "" {
+				t.Fatal(diff)
+			}
+			if flags.NArg() != 2 || flags.Arg(0) != "arg0" || flags.Arg(1) != "arg1" {
+				t.Fatalf("bad args: %q", flags.Args())
+			}
+		})
+	}
+}