Auto merge of #13910 - rwakulszowa:font-feature-settings, r=emilio

Font feature settings

<!-- Please describe your changes on the following line: -->
Implement parsing/serialization for font-feature-settings

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #13852 (github issue number if applicable).

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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tests/unit/style/parsing/font.rs

@@ -0,0 +1,78 @@
+/* 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 cssparser::Parser;
+use media_queries::CSSErrorReporterTest;
+use style::parser::ParserContext;
+use style::properties::longhands::font_feature_settings;
+use style::properties::longhands::font_feature_settings::computed_value;
+use style::properties::longhands::font_feature_settings::computed_value::FeatureTagValue;
+use style::stylesheets::Origin;
+use url::Url;
+
+#[test]
+fn font_feature_settings_should_parse_properly() {
+    let normal = parse_longhand!(font_feature_settings, "normal");
+    let normal_computed = computed_value::T::Normal;
+    assert_eq!(normal, normal_computed);
+
+    let on = parse_longhand!(font_feature_settings, "\"abcd\" on");
+    let on_computed = computed_value::T::Tag(vec![
+        FeatureTagValue { tag: String::from("abcd"), value: 1 }
+    ]);
+    assert_eq!(on, on_computed);
+
+    let off = parse_longhand!(font_feature_settings, "\"abcd\" off");
+    let off_computed = computed_value::T::Tag(vec![
+        FeatureTagValue { tag: String::from("abcd"), value: 0 }
+    ]);
+    assert_eq!(off, off_computed);
+
+    let no_value = parse_longhand!(font_feature_settings, "\"abcd\"");
+    let no_value_computed = computed_value::T::Tag(vec![
+        FeatureTagValue { tag: String::from("abcd"), value: 1 }
+    ]);
+    assert_eq!(no_value, no_value_computed);
+
+    let pos_integer = parse_longhand!(font_feature_settings, "\"abcd\" 100");
+    let pos_integer_computed = computed_value::T::Tag(vec![
+        FeatureTagValue { tag: String::from("abcd"), value: 100 }
+    ]);
+    assert_eq!(pos_integer, pos_integer_computed);
+
+    let multiple = parse_longhand!(font_feature_settings, "\"abcd\" off, \"efgh\"");
+    let multiple_computed = computed_value::T::Tag(vec![
+        FeatureTagValue { tag: String::from("abcd"), value: 0 },
+        FeatureTagValue { tag: String::from("efgh"), value: 1 }
+    ]);
+    assert_eq!(multiple, multiple_computed);
+}
+
+#[test]
+fn font_feature_settings_should_throw_on_bad_input() {
+    let url = Url::parse("http://localhost").unwrap();
+    let context = ParserContext::new(Origin::Author, &url, Box::new(CSSErrorReporterTest));
+
+    let mut empty = Parser::new("");
+    assert!(font_feature_settings::parse(&context, &mut empty).is_err());
+
+    let mut negative = Parser::new("\"abcd\" -1");
+    assert!(font_feature_settings::parse(&context, &mut negative).is_err());
+
+    let mut short_tag = Parser::new("\"abc\"");
+    assert!(font_feature_settings::parse(&context, &mut short_tag).is_err());
+
+    let mut illegal_tag = Parser::new("\"abcó\"");
+    assert!(font_feature_settings::parse(&context, &mut illegal_tag).is_err());
+}
+
+#[test]
+fn font_feature_settings_to_css() {
+    assert_roundtrip_with_context!(font_feature_settings::parse, "normal");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\"");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" on", "\"abcd\"");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" off");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" 4");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\", \"efgh\"");
+}

tests/unit/style/parsing/mod.rs

@@ -62,6 +62,7 @@ macro_rules! parse_longhand {
 }
 
 mod basic_shape;
+mod font;
 mod image;
 mod inherited_text;
 mod mask;