Break the fs package up into smaller parts.

The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.

The new code layout is documented in CONTRIBUTING.

fs/sizesuffix_test.go

@@ -0,0 +1,90 @@
+package fs
+
+import (
+	"testing"
+
+	"github.com/spf13/pflag"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// Check it satisfies the interface
+var _ pflag.Value = (*SizeSuffix)(nil)
+
+func TestSizeSuffixString(t *testing.T) {
+	for _, test := range []struct {
+		in   float64
+		want string
+	}{
+		{0, "0"},
+		{102, "102"},
+		{1024, "1k"},
+		{1024 * 1024, "1M"},
+		{1024 * 1024 * 1024, "1G"},
+		{10 * 1024 * 1024 * 1024, "10G"},
+		{10.1 * 1024 * 1024 * 1024, "10.100G"},
+		{-1, "off"},
+		{-100, "off"},
+	} {
+		ss := SizeSuffix(test.in)
+		got := ss.String()
+		assert.Equal(t, test.want, got)
+	}
+}
+
+func TestSizeSuffixUnit(t *testing.T) {
+	for _, test := range []struct {
+		in   float64
+		want string
+	}{
+		{0, "0 Bytes"},
+		{102, "102 Bytes"},
+		{1024, "1 kBytes"},
+		{1024 * 1024, "1 MBytes"},
+		{1024 * 1024 * 1024, "1 GBytes"},
+		{10 * 1024 * 1024 * 1024, "10 GBytes"},
+		{10.1 * 1024 * 1024 * 1024, "10.100 GBytes"},
+		{-1, "off"},
+		{-100, "off"},
+	} {
+		ss := SizeSuffix(test.in)
+		got := ss.Unit("Bytes")
+		assert.Equal(t, test.want, got)
+	}
+}
+
+func TestSizeSuffixSet(t *testing.T) {
+	for _, test := range []struct {
+		in   string
+		want int64
+		err  bool
+	}{
+		{"0", 0, false},
+		{"1b", 1, false},
+		{"102B", 102, false},
+		{"0.1k", 102, false},
+		{"0.1", 102, false},
+		{"1K", 1024, false},
+		{"1", 1024, false},
+		{"2.5", 1024 * 2.5, false},
+		{"1M", 1024 * 1024, false},
+		{"1.g", 1024 * 1024 * 1024, false},
+		{"10G", 10 * 1024 * 1024 * 1024, false},
+		{"off", -1, false},
+		{"OFF", -1, false},
+		{"", 0, true},
+		{"1p", 0, true},
+		{"1.p", 0, true},
+		{"1p", 0, true},
+		{"-1K", 0, true},
+	} {
+		ss := SizeSuffix(0)
+		err := ss.Set(test.in)
+		if test.err {
+			require.Error(t, err)
+		} else {
+			require.NoError(t, err)
+		}
+		assert.Equal(t, test.want, int64(ss))
+	}
+}