fix(python) identifiers starting with underscore not highlighted

Since hljs version 11, python identifiers starting with an underscore
character were no longer highlighted (regression introduced in 952fa0a).

Add new python markup test related to identifiers highlighting.

CHANGES.md

@@ -2,11 +2,13 @@
 
 Grammars:
 
+- fix(python) identifiers starting with underscore not highlighted (#3221) [Antoine Lambert][]
 - enh(clojure) added `edn` alias (#3213) [Stel Abrego][]
 - enh(elixir) much improved regular expression sigil support (#3207) [Josh Goebel][]
 
 [Stel Abrego]: https://github.com/stelcodes
 [Josh Goebel]: https://github.com/joshgoebel
+[Antoine Lambert]: https://github.com/anlambert
 
 ## Version 11.0.0
 

src/languages/python.js

@@ -5,7 +5,7 @@ Website: https://www.python.org
 Category: common
 */
 
-import { IDENT_RE } from '../lib/modes.js';
+import { UNDERSCORE_IDENT_RE } from '../lib/modes.js';
 import * as regex from '../lib/regex.js';
 
 export default function(hljs) {
@@ -379,7 +379,7 @@ export default function(hljs) {
       {
         match: [
           /def/, /\s+/,
-          IDENT_RE
+          UNDERSCORE_IDENT_RE
         ],
         scope: {
           1: "keyword",
@@ -392,14 +392,14 @@ export default function(hljs) {
           {
             match: [
               /class/, /\s+/,
-              IDENT_RE, /\s*/,
-              /\(\s*/, IDENT_RE,/\s*\)/
+              UNDERSCORE_IDENT_RE, /\s*/,
+              /\(\s*/, UNDERSCORE_IDENT_RE,/\s*\)/
             ],
           },
           {
             match: [
               /class/, /\s+/,
-              IDENT_RE
+              UNDERSCORE_IDENT_RE
             ],
           }
         ],

test/markup/python/identifiers.expect.txt

@@ -0,0 +1,15 @@
+<span class="hljs-keyword">def</span> <span class="hljs-title function_">func</span>():
+    <span class="hljs-keyword">pass</span>
+
+<span class="hljs-keyword">def</span> <span class="hljs-title function_">_private_func</span>():
+    <span class="hljs-keyword">pass</span>
+
+<span class="hljs-keyword">class</span> <span class="hljs-title class_">IdentifiersTest</span>:
+    <span class="hljs-keyword">def</span> <span class="hljs-title function_">__init__</span>(<span class="hljs-params">self</span>):
+        <span class="hljs-keyword">pass</span>
+
+    <span class="hljs-keyword">def</span> <span class="hljs-title function_">method</span>(<span class="hljs-params">self</span>):
+        <span class="hljs-keyword">pass</span>
+
+<span class="hljs-keyword">class</span> <span class="hljs-title class_">_PrivateClass</span>:
+    <span class="hljs-keyword">pass</span>

test/markup/python/identifiers.txt

@@ -0,0 +1,15 @@
+def func():
+    pass
+
+def _private_func():
+    pass
+
+class IdentifiersTest:
+    def __init__(self):
+        pass
+
+    def method(self):
+        pass
+
+class _PrivateClass:
+    pass