[lang2/macro] add test for unknown ink! method marker

lang2/macro/tests/compile_tests.rs

@@ -43,4 +43,5 @@ fn compile_tests() {
     t.compile_fail("tests/ui/fail/17-conflicting-ink-markers.rs");
     t.compile_fail("tests/ui/fail/18-conflicting-ink-markers-2.rs");
     t.compile_fail("tests/ui/fail/19-unknown-struct-ink-marker.rs");
+    t.compile_fail("tests/ui/fail/20-unknown-method-marker.rs");
 }

lang2/macro/tests/ui/fail/20-unknown-method-marker.rs

+#![feature(proc_macro_hygiene)]
+
+use ink_lang2 as ink;
+
+#[ink::contract(version = "0.1.0")]
+mod noop {
+    #[ink(storage)]
+    struct Noop {}
+
+    impl Noop {
+        #[ink(constructor)]
+        fn new(&mut self) {}
+
+        #[ink(message)]
+        fn noop(&self) {}
+
+        #[ink(unknown_marker)]
+        fn has_unknown_marker(&self) {}
+
+        #[ink(unknown_marker_2)]
+        fn has_unknown_marker_too(&mut self) {}
+    }
+}
+
+fn main() {}

lang2/macro/tests/ui/fail/20-unknown-method-marker.stderr

+error: unknown ink! marker
+  --> $DIR/20-unknown-method-marker.rs:17:14
+   |
+17 |         #[ink(unknown_marker)]
+   |              ^^^^^^^^^^^^^^^^