diff --git a/src/commands.rs b/src/commands.rs
index a2fcf66..a3d7ed5 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -374,3 +374,66 @@ fn key_value_pair(s: &'static str) -> Option<&'static str> {
         })
         .flatten()
 }
+
+mod test {
+    use super::*;
+
+    #[test]
+    fn existing_commands_are_parsed_as_expected() {
+        macro_rules! params {
+            ($(($key:literal, $value:literal)),+) => (
+                [$(($key, $value)),+].iter().fold(
+                        HashMap::new(),
+                        |mut hash_map, pair| {
+                            hash_map.insert(pair.0, pair.1);
+                            hash_map
+                        },
+                )
+            );
+        }
+
+        let mut cmds = Commands::new();
+
+        cmds.add("?tags delete {key}", |_: Args| Ok(()));
+        cmds.add("?tags create {key} value...", |_: Args| Ok(()));
+        cmds.add("?tags update {key} value...", |_: Args| Ok(()));
+        cmds.add("?tag {key}", |_: Args| Ok(()));
+        cmds.add("?tags", |_: Args| Ok(()));
+
+        cmds.add("?crate query...", |_: Args| Ok(()));
+
+        // tags
+
+        let tags_delete = cmds.state_machine.process("?tags delete foo");
+        assert!(tags_delete.is_some());
+        tags_delete.map(|matched| assert!(params!(("key", "foo")) == matched.params));
+
+        let tags_create = cmds.state_machine.process("?tags create foo foo bar baz");
+        assert!(tags_create.is_some());
+        tags_create.map(|matched| {
+            assert!(params!(("key", "foo"), ("value", "foo bar baz")) == matched.params);
+        });
+
+        let tags_update = cmds.state_machine.process("?tags update foo 123 456 abc");
+        assert!(tags_update.is_some());
+        tags_update.map(|matched| {
+            assert!(params!(("key", "foo"), ("value", "123 456 abc")) == matched.params);
+        });
+
+        let tag = cmds.state_machine.process("?tag foo");
+        assert!(tag.is_some());
+        tag.map(|matched| {
+            assert!(params!(("key", "foo")) == matched.params);
+        });
+
+        assert!(cmds.state_machine.process("?tags").is_some());
+
+        // crates
+
+        let krate = cmds.state_machine.process("?crate 12345abc");
+        assert!(krate.is_some());
+        krate.map(|matched| {
+            assert!(params!(("query", "12345abc")) == matched.params);
+        });
+    }
+}