Allow --pre option in requirement files

closes #1273

CHANGES.txt

@@ -18,6 +18,8 @@
 
 * Allow ``--process-dependency-links`` within a requirements file. :issue:`1274`.
 
+* Allow ``--pre`` within a requirements file. :issue:`1273`.
+
 
 **7.1.2 (2015-08-22)**
 

pip/cmdoptions.py

@@ -496,6 +496,14 @@ no_clean = partial(
     default=False,
     help="Don't clean up build directories.")
 
+pre = partial(
+    Option,
+    '--pre',
+    action='store_true',
+    default=False,
+    help="Include pre-release and development versions. By default, "
+         "pip only finds stable versions.")
+
 disable_pip_version_check = partial(
     Option,
     "--disable-pip-version-check",

pip/commands/install.py

@@ -156,13 +156,7 @@ class InstallCommand(RequirementCommand):
         cmd_opts.add_option(cmdoptions.no_use_wheel())
         cmd_opts.add_option(cmdoptions.no_binary())
         cmd_opts.add_option(cmdoptions.only_binary())
-
-        cmd_opts.add_option(
-            '--pre',
-            action='store_true',
-            default=False,
-            help="Include pre-release and development versions. By default, "
-                 "pip only finds stable versions.")
+        cmd_opts.add_option(cmdoptions.pre())
 
         cmd_opts.add_option(cmdoptions.no_clean())
 

pip/req/req_file.py

@@ -43,6 +43,7 @@ SUPPORTED_OPTIONS = [
     cmdoptions.always_unzip,
     cmdoptions.no_binary,
     cmdoptions.only_binary,
+    cmdoptions.pre,
     cmdoptions.process_dependency_links,
     cmdoptions.trusted_host,
 ]
@@ -220,6 +221,8 @@ def process_line(line, filename, line_number, finder=None, comes_from=None,
             if os.path.exists(relative_to_reqs_file):
                 value = relative_to_reqs_file
             finder.find_links.append(value)
+        if opts.pre:
+            finder.allow_all_prereleases = True
         if opts.process_dependency_links:
             finder.process_dependency_links = True
         if opts.trusted_hosts:

tests/unit/test_req_file.py

@@ -214,6 +214,10 @@ class TestProcessLine(object):
         # noop, but confirm it can be set
         list(process_line("--no-allow-insecure", "file", 1, finder=finder))
 
+    def test_set_finder_allow_all_prereleases(self, finder):
+        list(process_line("--pre", "file", 1, finder=finder))
+        assert finder.allow_all_prereleases
+
     def test_relative_local_find_links(self, finder, monkeypatch):
         """
         Test a relative find_links path is joined with the req file directory