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/dump_test.go

@@ -0,0 +1,58 @@
+package fs
+
+import (
+	"testing"
+
+	"github.com/spf13/pflag"
+	"github.com/stretchr/testify/assert"
+)
+
+// Check it satisfies the interface
+var _ pflag.Value = (*DumpFlags)(nil)
+
+func TestDumpFlagsString(t *testing.T) {
+	assert.Equal(t, "", DumpFlags(0).String())
+	assert.Equal(t, "headers", (DumpHeaders).String())
+	assert.Equal(t, "headers,bodies", (DumpHeaders | DumpBodies).String())
+	assert.Equal(t, "headers,bodies,requests,responses,auth,filters", (DumpHeaders | DumpBodies | DumpRequests | DumpResponses | DumpAuth | DumpFilters).String())
+	assert.Equal(t, "headers,Unknown-0x8000", (DumpHeaders | DumpFlags(0x8000)).String())
+}
+
+func TestDumpFlagsSet(t *testing.T) {
+	for _, test := range []struct {
+		in      string
+		want    DumpFlags
+		wantErr string
+	}{
+		{"", DumpFlags(0), ""},
+		{"bodies", DumpBodies, ""},
+		{"bodies,headers,auth", DumpBodies | DumpHeaders | DumpAuth, ""},
+		{"bodies,headers,auth", DumpBodies | DumpHeaders | DumpAuth, ""},
+		{"headers,bodies,requests,responses,auth,filters", DumpHeaders | DumpBodies | DumpRequests | DumpResponses | DumpAuth | DumpFilters, ""},
+		{"headers,bodies,unknown,auth", 0, "Unknown dump flag \"unknown\""},
+	} {
+		f := DumpFlags(-1)
+		initial := f
+		err := f.Set(test.in)
+		if err != nil {
+			if test.wantErr == "" {
+				t.Errorf("Got an error when not expecting one on %q: %v", test.in, err)
+			} else {
+				assert.Contains(t, err.Error(), test.wantErr)
+			}
+			assert.Equal(t, initial, f, test.want)
+		} else {
+			if test.wantErr != "" {
+				t.Errorf("Got no error when expecting one on %q", test.in)
+			} else {
+				assert.Equal(t, test.want, f)
+			}
+		}
+
+	}
+}
+
+func TestDumpFlagsType(t *testing.T) {
+	f := DumpFlags(0)
+	assert.Equal(t, "string", f.Type())
+}