This is the v1 version, had the v2 before.

backend/backendutil/flags_test.go

@@ -0,0 +1,86 @@
+package backendutil
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/emersion/go-imap"
+)
+
+var updateFlagsTests = []struct {
+	op    imap.FlagsOp
+	flags []string
+	res   []string
+}{
+	{
+		op:    imap.AddFlags,
+		flags: []string{"d", "e"},
+		res:   []string{"a", "b", "c", "d", "e"},
+	},
+	{
+		op:    imap.AddFlags,
+		flags: []string{"a", "d", "b"},
+		res:   []string{"a", "b", "c", "d"},
+	},
+	{
+		op:    imap.RemoveFlags,
+		flags: []string{"b", "v", "e", "a"},
+		res:   []string{"c"},
+	},
+	{
+		op:    imap.SetFlags,
+		flags: []string{"a", "d", "e"},
+		res:   []string{"a", "d", "e"},
+	},
+	// Test unknown op for code coverage.
+	{
+		op:    imap.FlagsOp("TestUnknownOp"),
+		flags: []string{"a", "d", "e"},
+		res:   []string{"a", "b", "c"},
+	},
+}
+
+func TestUpdateFlags(t *testing.T) {
+	flagsList := []string{"a", "b", "c"}
+	for _, test := range updateFlagsTests {
+		// Make a backup copy of 'test.flags'
+		origFlags := append(test.flags[:0:0], test.flags...)
+		// Copy flags
+		current := append(flagsList[:0:0], flagsList...)
+		got := UpdateFlags(current, test.op, test.flags)
+
+		if !reflect.DeepEqual(got, test.res) {
+			t.Errorf("Expected result to be \n%v\n but got \n%v", test.res, got)
+		}
+		// Verify that 'test.flags' wasn't modified
+		if !reflect.DeepEqual(origFlags, test.flags) {
+			t.Errorf("Unexpected change to operation flags list changed \nbefore %v\n after \n%v",
+				origFlags, test.flags)
+		}
+	}
+}
+
+func TestUpdateFlags_Recent(t *testing.T) {
+	current := []string{}
+
+	current = UpdateFlags(current, imap.SetFlags, []string{imap.RecentFlag})
+
+	res := []string{imap.RecentFlag}
+	if !reflect.DeepEqual(current, res) {
+		t.Errorf("Expected result to be \n%v\n but got \n%v", res, current)
+	}
+
+	current = UpdateFlags(current, imap.SetFlags, []string{"something"})
+
+	res = []string{imap.RecentFlag, "something"}
+	if !reflect.DeepEqual(current, res) {
+		t.Errorf("Expected result to be \n%v\n but got \n%v", res, current)
+	}
+
+	current = UpdateFlags(current, imap.SetFlags, []string{"another", imap.RecentFlag})
+
+	res = []string{imap.RecentFlag, "another"}
+	if !reflect.DeepEqual(current, res) {
+		t.Errorf("Expected result to be \n%v\n but got \n%v", res, current)
+	}
+}