Move sanity checks to stylo tests

tests/unit/stylo/Cargo.toml

@@ -12,5 +12,6 @@ doctest = false
 [dependencies]
 app_units = "0.3"
 cssparser = {version = "0.7", features = ["heap_size"]}
+gecko_bindings = {path = "../../../ports/geckolib/gecko_bindings"}
 style = {path = "../../../components/style", features = ["gecko"]}
 style_traits = {path = "../../../components/style_traits"}

tests/unit/stylo/lib.rs

@@ -1,10 +1,11 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
 extern crate app_units;
 extern crate cssparser;
+extern crate gecko_bindings;
 extern crate style;
 extern crate style_traits;
 
-#[test]
-fn test_test() {
-    // do nothing
-    // this is a temporary test testing that the test runs
-}
+mod sanity_checks;

tests/unit/stylo/sanity_checks.rs

@@ -0,0 +1,69 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+//! Different static asserts that ensure the build does what it's expected to.
+//!
+//! TODO: maybe cfg(test) this?
+
+#![allow(unused_imports)]
+
+use std::mem;
+
+macro_rules! check_enum_value {
+    ($a:expr, $b:expr) => {
+        unsafe {
+            mem::transmute::<[u32; $a as usize],
+                             [u32; $b as usize]>([0; $a as usize]);
+        }
+    }
+}
+
+// NB: It's a shame we can't do this statically with bitflags, but no
+// const-fn and no other way to access the numerical value :-(
+macro_rules! check_enum_value_non_static {
+    ($a:expr, $b:expr) => {
+        assert_eq!($a as usize, $b as usize);
+    }
+}
+
+#[test]
+fn assert_restyle_hints_match() {
+    use style::restyle_hints::*; // For flags
+    use gecko_bindings::structs::nsRestyleHint;
+
+    check_enum_value_non_static!(nsRestyleHint::eRestyle_Self, RESTYLE_SELF.bits());
+    // XXX This for Servo actually means something like an hypothetical
+    // Restyle_AllDescendants (but without running selector matching on the
+    // element). ServoRestyleManager interprets it like that, but in practice we
+    // should align the behavior with Gecko adding a new restyle hint, maybe?
+    //
+    // See https://bugzilla.mozilla.org/show_bug.cgi?id=1291786
+    check_enum_value_non_static!(nsRestyleHint::eRestyle_SomeDescendants, RESTYLE_DESCENDANTS.bits());
+    check_enum_value_non_static!(nsRestyleHint::eRestyle_LaterSiblings, RESTYLE_LATER_SIBLINGS.bits());
+}
+
+// Note that we can't call each_pseudo_element, parse_pseudo_element, or
+// similar, because we'd need the foreign atom symbols to link.
+#[test]
+fn assert_basic_pseudo_elements() {
+    let mut saw_before = false;
+    let mut saw_after = false;
+
+    macro_rules! pseudo_element {
+        (":before", $atom:expr, false) => {
+            saw_before = true;
+        };
+        (":after", $atom:expr, false) => {
+            saw_after = true;
+        };
+        ($pseudo_str_with_colon:expr, $atom:expr, $is_anon_box:expr) => {
+            // Do nothing
+        };
+    }
+
+    include!("../../../components/style/generated/gecko_pseudo_element_helper.rs");
+
+    assert!(saw_before);
+    assert!(saw_after);
+}