From 30a47e199a990c2fb6f7371490170dc7231d875c Mon Sep 17 00:00:00 2001
From: Jonathan Felchlin <jonathan@energysavvy.com>
Date: Tue, 26 Mar 2019 22:30:48 -0700
Subject: [PATCH] fix: Discarding used font-families due to mixed quotation
 types

---
 .../src/__tests__/index.js                    | 18 ++++++++-----
 packages/postcss-discard-unused/src/index.js  | 26 +++++++++----------
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/packages/postcss-discard-unused/src/__tests__/index.js b/packages/postcss-discard-unused/src/__tests__/index.js
index 56bb24be5..dc31214ed 100644
--- a/packages/postcss-discard-unused/src/__tests__/index.js
+++ b/packages/postcss-discard-unused/src/__tests__/index.js
@@ -75,21 +75,27 @@ test(
 test(
     'should remove unused fonts & keep used fonts',
     processCSS,
-    '@font-face {font-family:"Does Not Exist";src:url("fonts/does-not-exist.ttf") format("truetype")}@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font-family:"Does Exist",Helvetica,Arial,sans-serif}',
-    '@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font-family:"Does Exist",Helvetica,Arial,sans-serif}'
+    '@font-face {font-family:"Does Not Exist";src:url("fonts/does-not-exist.ttf") format("truetype")}@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font-family: "Does Exist", Helvetica, Arial, sans-serif}',
+    '@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font-family: "Does Exist", Helvetica, Arial, sans-serif}'
 );
 
 test(
     'should work with the font shorthand',
     passthroughCSS,
-    '@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font: 10px/1.5 "Does Exist",Helvetica,Arial,sans-serif}'
+    '@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font: 10px/1.5 "Does Exist", Helvetica, Arial, sans-serif}'
 );
 
 test(
-    'should not be responsible for normalising fonts',
+    'should work with mixed quote styles',
+    passthroughCSS,
+    '@font-face {font-family:"Does Exist";src:url("fonts/does-exist.ttf") format("truetype")}@font-face {font-family:\'DoesExist\';src:url("fonts/does-exist.ttf") format("truetype")}body{font-family: Does Exist; font: 10px DoesExist}'
+);
+
+test(
+    "should handle font properties that don't include a font-family",
     processCSS,
-    '@font-face {font-family:"Does Exist";src:url("fonts/does-exist.ttf") format("truetype")}body{font-family:Does Exist}',
-    'body{font-family:Does Exist}'
+    '@font-face {font-family:"Does Exist";src: url("fonts/does-exist.ttf") format("truetype")}body{font: italic bold 10px/1.5}',
+    'body{font: italic bold 10px/1.5}'
 );
 
 test(
diff --git a/packages/postcss-discard-unused/src/index.js b/packages/postcss-discard-unused/src/index.js
index 7bc03b6ee..edca0a10f 100644
--- a/packages/postcss-discard-unused/src/index.js
+++ b/packages/postcss-discard-unused/src/index.js
@@ -8,6 +8,11 @@ const atrule = 'atrule';
 const decl = 'decl';
 const rule = 'rule';
 
+function normalizeFontName (value) {
+    // Ignore casing and wrapping quotes when checking for font use.
+    return value.toLowerCase().replace(/^\s*(['"])(.*?)(\1)\s*$/, '$2');
+}
+
 function addValues (cache, {value}) {
     return comma(value).reduce((memo, val) => [...memo, ...space(val)], cache);
 }
@@ -36,24 +41,15 @@ function filterNamespace ({atRules, rules}) {
     });
 }
 
-function hasFont (fontFamily, cache) {
-    return comma(fontFamily).some(font => cache.some(c => ~c.indexOf(font)));
-}
-
 // fonts have slightly different logic
 function filterFont ({atRules, values}) {
     values = uniqs(values);
     atRules.forEach(r => {
-        const families = r.nodes.filter(({prop}) => prop === 'font-family');
-        // Discard the @font-face if it has no font-family
-        if (!families.length) {
-            return r.remove();
+        const fontFamilyRule = r.nodes.find(({prop}) => prop === 'font-family');
+        // Discard the @font-face if it has no font-family rule or if it is unused
+        if (!fontFamilyRule || !values.includes(normalizeFontName(fontFamilyRule.value))) {
+            r.remove();
         }
-        families.forEach(family => {
-            if (!hasFont(family.value.toLowerCase(), values)) {
-                r.remove();
-            }
-        });
     });
 }
 
@@ -94,7 +90,9 @@ export default plugin('postcss-discard-unused', opts => {
                     counterStyleCache.values = addValues(counterStyleCache.values, node);
                 }
                 if (fontFace && node.parent.type === rule && /font(|-family)/.test(prop)) {
-                    fontCache.values = fontCache.values.concat(comma(node.value.toLowerCase()));
+                    const fontFamilies = prop === 'font-family' ? comma(node.value) :
+                        [].concat(...space(node.value).map(comma));
+                    fontCache.values.push(...fontFamilies.map(normalizeFontName));
                 }
                 if (keyframes && /animation/.test(prop)) {
                     keyframesCache.values = addValues(keyframesCache.values, node);