Auto merge of #17974 - froydnj:remove-testing-feature, r=SimonSapin

remove testing feature from stylo_tests

`stylo_tests` currently requires a separate version of the `style` crate, compiled with the `testing` feature, so a function testing the size of specified values can be accessed.  With a few tweaks, we can make the information needed for the test available to the `stylo_tests` crate directly, eliminating the need for a separately-compiled `style` crate.

This doesn't matter much for Servo itself (it might make CI times slightly faster?), but Gecko automation/development would like to run `stylo_tests`, and not having to compile two versions of the `style` crate (or have a dead, test-only function hanging around in the `style` crate) would be a win.

---

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] There are tests for these changes

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tests/unit/style/Cargo.toml

@@ -9,9 +9,6 @@ name = "style_tests"
 path = "lib.rs"
 doctest = false
 
-[features]
-testing = ["style/testing"]
-
 [dependencies]
 byteorder = "1.0"
 app_units = "0.5"

tests/unit/style/lib.rs

@@ -19,7 +19,7 @@ extern crate servo_atoms;
 extern crate servo_config;
 extern crate servo_url;
 #[macro_use] extern crate size_of_test;
-extern crate style;
+#[macro_use] extern crate style;
 extern crate style_traits;
 extern crate test;
 
@@ -32,6 +32,8 @@ mod parsing;
 mod properties;
 mod rule_tree;
 mod size_of;
+#[path = "../stylo/specified_values.rs"]
+mod specified_values;
 mod str;
 mod stylesheets;
 mod stylist;

tests/unit/style/size_of.rs

@@ -12,8 +12,3 @@ size_of_test!(test_size_of_property_declaration, properties::PropertyDeclaration
 // This is huge, but we allocate it on the stack and then never move it,
 // we only pass `&mut SourcePropertyDeclaration` references around.
 size_of_test!(test_size_of_parsed_declaration, properties::SourcePropertyDeclaration, 576);
-
-#[test]
-fn size_of_specified_values() {
-    ::style::properties::test_size_of_specified_values();
-}

tests/unit/stylo/Cargo.toml

@@ -11,9 +11,6 @@ name = "stylo_tests"
 path = "lib.rs"
 doctest = false
 
-[features]
-testing = ["style/testing"]
-
 [dependencies]
 atomic_refcell = "0.1"
 cssparser = "0.18"

tests/unit/stylo/lib.rs

@@ -14,6 +14,7 @@ extern crate style_traits;
 
 mod sanity_checks;
 mod size_of;
+mod specified_values;
 
 mod servo_function_signatures;
 

tests/unit/stylo/size_of.rs

@@ -47,8 +47,3 @@ size_of_test!(test_size_of_rule_node, RuleNode, 80);
 // This is huge, but we allocate it on the stack and then never move it,
 // we only pass `&mut SourcePropertyDeclaration` references around.
 size_of_test!(test_size_of_parsed_declaration, style::properties::SourcePropertyDeclaration, 704);
-
-#[test]
-fn size_of_specified_values() {
-    ::style::properties::test_size_of_specified_values();
-}

tests/unit/stylo/specified_values.rs

@@ -0,0 +1,49 @@
+/* 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/. */
+
+use style;
+
+#[test]
+fn size_of_specified_values() {
+    use std::mem::size_of;
+    let threshold = 24;
+
+    let mut bad_properties = vec![];
+
+    macro_rules! check_property {
+        ( $( { $name: ident, $boxed: expr } )+ ) => {
+            $(
+                let size = size_of::<style::properties::longhands::$name::SpecifiedValue>();
+                let is_boxed = $boxed;
+                if (!is_boxed && size > threshold) || (is_boxed && size <= threshold) {
+                    bad_properties.push(("$name", size, is_boxed));
+                }
+            )+
+        }
+    }
+
+    longhand_properties_idents!(check_property);
+
+    let mut failing_messages = vec![];
+
+    for bad_prop in bad_properties {
+        if !bad_prop.2 {
+            failing_messages.push(
+                format!("Your changes have increased the size of {} SpecifiedValue to {}. The threshold is \
+                        currently {}. SpecifiedValues affect size of PropertyDeclaration enum and \
+                        increasing the size may negative affect style system performance. Please consider \
+                        using `boxed=\"True\"` in this longhand.",
+                        bad_prop.0, bad_prop.1, threshold));
+        } else if bad_prop.2 {
+            failing_messages.push(
+                format!("Your changes have decreased the size of {} SpecifiedValue to {}. Good work! \
+                        The threshold is currently {}. Please consider removing `boxed=\"True\"` from this longhand.",
+                        bad_prop.0, bad_prop.1, threshold));
+        }
+    }
+
+    if !failing_messages.is_empty() {
+        panic!("{}", failing_messages.join("\n\n"));
+    }
+}