Add a few more test cases

Author: DJMcNab

fearless_simd_core/src/support.rs

@@ -199,6 +199,8 @@ mod tests {
         expect_failure("c,a,b", [&["a", "b"]], "c");
         expect_success("a,b", [&["a", "b", "c"]]);
         expect_failure("a,b", [&["a", "c"]], "b");
+        expect_success("a,b,a,a", [&["a", "b", "c"]]);
+        expect_success("a,b,c", [&["c"], &["b"], &["a"]]);
 
         // Check it correctly catches more than single item failures
         expect_success("a1,a2,a3", [&["a1", "a2", "a3"]]);
@@ -220,10 +222,23 @@ mod tests {
         expect_failure("a1b,a2b", [&["a1b", "a3b"]], "a2b");
     }
 
+    #[test]
+    fn incorrect_token() {
+        // The permitted list here only allows features which are the literal `a1,a2`
+        // This is completely impossible to pass, but it's worth checking
+        expect_any_failure("a1,a2", [&["a1,a2"]]);
+    }
+
     #[test]
     fn empty_feature() {
         expect_failure("a,b,", [&["a", "b"]], "");
         expect_failure("", [&["a", "b"]], "");
+
+        // We succeed if the empty target feature is allowed; any case where this is relevant will always
+        // be validated away by rustc anyway, as there is no target with the target feature `""`.
+        // As such, there's no harm in being flexible here.
+        expect_success("", [&[""]]);
+        expect_success(",,,,,,", [&[""]]);
     }
 
     #[test]