Centralize ParserContext for tests

To simplify adding additional data to `ParserContext`, this moves test usages to
a few shared locations, instead of being spread across many tests.

MozReview-Commit-ID: 1OahV797eq

tests/unit/style/properties/mod.rs

@@ -2,6 +2,42 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use cssparser::Parser;
+use media_queries::CSSErrorReporterTest;
+use style::parser::ParserContext;
+use style::stylesheets::{CssRuleType, Origin};
+
+fn parse<T, F: Fn(&ParserContext, &mut Parser) -> Result<T, ()>>(f: F, s: &str) -> Result<T, ()> {
+    let url = ::servo_url::ServoUrl::parse("http://localhost").unwrap();
+    let reporter = CSSErrorReporterTest;
+    let context = ParserContext::new(Origin::Author, &url, &reporter, Some(CssRuleType::Style));
+    let mut parser = Parser::new(s);
+    f(&context, &mut parser)
+}
+
+macro_rules! assert_roundtrip_with_context {
+    ($fun:expr, $string:expr) => {
+        assert_roundtrip_with_context!($fun, $string, $string);
+    };
+    ($fun:expr, $input:expr, $output:expr) => {{
+        let serialized = parse(|context, i| {
+            let parsed = $fun(context, i)
+                         .expect(&format!("Failed to parse {}", $input));
+            let serialized = ToCss::to_css_string(&parsed);
+            assert_eq!(serialized, $output);
+            Ok(serialized)
+        }, $input).unwrap();
+
+        parse(|context, i| {
+            let re_parsed = $fun(context, i)
+                            .expect(&format!("Failed to parse serialization {}", $input));
+            let re_serialized = ToCss::to_css_string(&re_parsed);
+            assert_eq!(serialized, re_serialized);
+            Ok(())
+        }, &serialized).unwrap()
+    }}
+}
+
 mod background;
 mod scaffolding;
 mod serialization;