gh-113539: Enable using $BROWSER to reorder default seach order in webbrowser.py

Doc/library/webbrowser.rst

@@ -24,8 +24,17 @@ If the environment variable :envvar:`BROWSER` exists, it is interpreted as the
 :data:`os.pathsep`-separated list of browsers to try ahead of the platform
 defaults.  When the value of a list part contains the string ``%s``, then it is
 interpreted as a literal browser command line to be used with the argument URL
-substituted for ``%s``; if the part does not contain ``%s``, it is simply
-interpreted as the name of the browser to launch. [1]_
+substituted for ``%s``; if the value is a single word that refers to one of the
+already registered browsers this browser is added to the front of the search list;
+if the part does not contain ``%s``, it is simply interpreted as the name of the
+browser to launch. [1]_
+
+.. versionchanged:: 3.13
+
+   The :envvar:`BROWSER` variable can now also be used to reorder the list of
+   platform defaults. This is particularly useful on macOS where the platform
+   defaults do not refer to command-line tools on :envvar:`PATH`.
+
 
 For non-Unix platforms, or when a remote browser is available on Unix, the
 controlling process will not wait for the user to finish with the browser, but

Lib/webbrowser.py

@@ -466,10 +466,10 @@ def register_standard_browsers():
 
     if sys.platform == 'darwin':
         register("MacOSX", None, MacOSXOSAScript('default'))
-        register("chrome", None, MacOSXOSAScript('chrome'))
+        register("chrome", None, MacOSXOSAScript('google chrome'))
         register("firefox", None, MacOSXOSAScript('firefox'))
         register("safari", None, MacOSXOSAScript('safari'))
-        # OS X can use below Unix support (but we prefer using the OS X
+        # macOS can use below Unix support (but we prefer using the macOS
         # specific stuff)
 
     if sys.platform == "serenityos":
@@ -539,6 +539,19 @@ def register_standard_browsers():
         # Treat choices in same way as if passed into get() but do register
         # and prepend to _tryorder
         for cmdline in userchoices:
+            if all(x not in cmdline for x in " \t"):
+                # Assume this is the name of a registered command, use
+                # that unless it is a GenericBrowser.
+                try:
+                    command = _browsers[cmdline.lower()]
+                except KeyError:
+                    pass
+
+                else:
+                    if not isinstance(command[1], GenericBrowser):
+                        _tryorder.insert(0, cmdline.lower())
+                        continue
+
             if cmdline != '':
                 cmd = _synthesize(cmdline, preferred=True)
                 if cmd[1] is None:

Misc/NEWS.d/next/Library/2023-12-29-09-44-41.gh-issue-113539.YDkv9O.rst

@@ -0,0 +1,6 @@
+:mod:`webbrowser`: Names in the :envvar:`BROWSER` environment variable can now
+refer to already registered web browsers, instead of always generating a new
+browser command.
+
+This makes it possible to set :envvar:`BROWSER` to the value of one of the
+supported browsers on macOS.