Add more failing tests

Signed-off-by: Sasha Pourcelot <[email protected]>

tests/ui/fail/path.rs

@@ -0,0 +1,24 @@
+#![allow(unused)]
+
+#[expandable::expr]
+macro_rules! a {
+    () => {
+        path:::<foo>
+    };
+}
+
+#[expandable::expr]
+macro_rules! b {
+    () => {
+        path::< <foo> >
+    };
+}
+
+#[expandable::expr]
+macro_rules! c {
+    () => {
+        path::1
+    };
+}
+
+fn main() {}

tests/ui/fail/path.stderr

@@ -0,0 +1,17 @@
+error: Potentially invalid expansion. Expected `Self`, an identifier.
+ --> tests/ui/fail/path.rs:6:15
+  |
+6 |         path:::<foo>
+  |               ^
+
+error: Potentially invalid expansion. Expected `-`, `>`, a `{`, a literal, an identifier, an identifier.
+  --> tests/ui/fail/path.rs:13:17
+   |
+13 |         path::< <foo> >
+   |                 ^
+
+error: Potentially invalid expansion. Expected `Self`, an identifier.
+  --> tests/ui/fail/path.rs:20:15
+   |
+20 |         path::1
+   |               ^