Add unsubscribe command

The unsubscribe command, available when in a message viewer context,
enables users to easily unsubscribe from mailing lists.

When the command is executed, aerc looks for a List-Unsubscribe header
as defined in RFC 2369. If found, aerc will attempt to present the user
with a suitable interface for completing the request. Currently, mailto
and http(s) URLs are supported. In the case of a HTTP(S) URL, aerc will
open the link in a browser. For mailto links, a new composer tab will be
opened with a message filled out according to the URL. The message is
not sent automatically in order to provide the user a chance to review
it first.

Closes #101

1 files changed, 41 insertions, 0 deletions

diff --git a/commands/msg/unsubscribe_test.go b/commands/msg/unsubscribe_test.go
new file mode 100644
index 00000000..e4e6f25e
--- /dev/null
+++ b/commands/msg/unsubscribe_test.go
@@ -0,0 +1,41 @@
+package msg
+
+import (
+	"testing"
+)
+
+func TestParseUnsubscribe(t *testing.T) {
+	type tc struct {
+		hdr      string
+		expected []string
+	}
+	cases := []*tc{
+		&tc{"", []string{}},
+		&tc{"invalid", []string{}},
+		&tc{"<https://example.com>, <http://example.com>", []string{
+			"https://example.com", "http://example.com",
+		}},
+		&tc{"<https://example.com> is a URL", []string{
+			"https://example.com",
+		}},
+		&tc{"<mailto:user@host?subject=unsubscribe>, <https://example.com>",
+			[]string{
+				"mailto:user@host?subject=unsubscribe", "https://example.com",
+			}},
+		&tc{"<>, <https://example> ", []string{
+			"", "https://example",
+		}},
+	}
+	for _, c := range cases {
+		result := parseUnsubscribeMethods(c.hdr)
+		if len(result) != len(c.expected) {
+			t.Errorf("expected %d methods but got %d", len(c.expected), len(result))
+			continue
+		}
+		for idx := 0; idx < len(result); idx++ {
+			if result[idx].String() != c.expected[idx] {
+				t.Errorf("expected %v but got %v", c.expected[idx], result[idx])
+			}
+		}
+	}
+}