syntax: move error test to syntax crate

The problem with putting it in the regex crate proper is that it
requires the regex crate to bump its minimal regex-syntax crate version.
While this isn't necessarily an issue, since we can't enable Cargo's
minimal version check because of the `rand` dependency, this winds up
being a hazard. Plus, having it in the regex crate doesn't buy us too
much. It's just as well to have the tests in regex-syntax.

Fixes #593

CHANGELOG.md

@@ -1,15 +1,24 @@
+1.1.9 (2019-07-06)
+==================
+This release contains a bug fix that caused regex's tests to fail, due to a
+dependency on an unreleased behavior in regex-syntax.
+
+* [BUG #593](https://github.com/rust-lang/regex/issues/593):
+  Move an integration-style test on error messages into regex-syntax.
+
+
 1.1.8 (2019-07-04)
 ==================
 This release contains a few small internal refactorings. One of which fixes
 an instance of undefined behavior in a part of the SIMD code.
 
 Bug fixes:
 
-* [BUG #545](https://github.com/rust-lang/regex/pull/545):
+* [BUG #545](https://github.com/rust-lang/regex/issues/545):
   Improves error messages when a repetition operator is used without a number.
-* [BUG #588](https://github.com/rust-lang/regex/pull/588):
+* [BUG #588](https://github.com/rust-lang/regex/issues/588):
   Removes use of a repr(Rust) union used for type punning in the Teddy matcher.
-* [BUG #591](https://github.com/rust-lang/regex/pull/591):
+* [BUG #591](https://github.com/rust-lang/regex/issues/591):
   Update docs for running benchmarks and improve failure modes.
 
 

regex-syntax/src/error.rs

@@ -287,11 +287,34 @@ fn repeat_char(c: char, count: usize) -> String {
 mod tests {
     use ast::parse::Parser;
 
+    fn assert_panic_message(pattern: &str, expected_msg: &str) -> () {
+        let result = Parser::new().parse(pattern);
+        match result {
+            Ok(_) => {
+                panic!("regex should not have parsed");
+            }
+            Err(err) => {
+                assert_eq!(err.to_string(), expected_msg.trim());
+            }
+        }
+    }
+
     // See: https://github.com/rust-lang/regex/issues/464
     #[test]
     fn regression_464() {
         let err = Parser::new().parse("a{\n").unwrap_err();
         // This test checks that the error formatter doesn't panic.
         assert!(!err.to_string().is_empty());
     }
+
+    // See: https://github.com/rust-lang/regex/issues/545
+    #[test]
+    fn repetition_quantifier_expects_a_valid_decimal() {
+        assert_panic_message(r"\\u{[^}]*}", r#"
+regex parse error:
+    \\u{[^}]*}
+        ^
+error: repetition quantifier expects a valid decimal
+"#);
+    }
 }

tests/test_default.rs

@@ -67,7 +67,6 @@ mod suffix_reverse;
 mod unicode;
 mod word_boundary;
 mod word_boundary_unicode;
-mod error_messages;
 
 #[test]
 fn disallow_non_utf8() {