fs: Add ParseRangeOption to parse incoming Range: requests

fs/options_test.go

@@ -0,0 +1,39 @@
+package fs
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseRangeOption(t *testing.T) {
+	for _, test := range []struct {
+		in   string
+		want RangeOption
+		err  string
+	}{
+		{in: "", err: "doesn't start with bytes="},
+		{in: "bytes=1-2,3-4", err: "contains multiple ranges"},
+		{in: "bytes=100", err: "contains no '-'"},
+		{in: "bytes=x-8", err: "bad start"},
+		{in: "bytes=8-x", err: "bad end"},
+		{in: "bytes=1-2", want: RangeOption{Start: 1, End: 2}},
+		{in: "bytes=-123456789123456789", want: RangeOption{Start: -1, End: 123456789123456789}},
+		{in: "bytes=123456789123456789-", want: RangeOption{Start: 123456789123456789, End: -1}},
+		{in: "bytes=  1  -  2  ", want: RangeOption{Start: 1, End: 2}},
+		{in: "bytes=-", want: RangeOption{Start: -1, End: -1}},
+		{in: "bytes=  -  ", want: RangeOption{Start: -1, End: -1}},
+	} {
+		got, err := ParseRangeOption(test.in)
+		what := fmt.Sprintf("parsing %q", test.in)
+		if test.err != "" {
+			require.Contains(t, err.Error(), test.err)
+			require.Nil(t, got, what)
+		} else {
+			require.NoError(t, err, what)
+			assert.Equal(t, test.want, *got, what)
+		}
+	}
+}