support None arguments. pru will solve on requirements

src/pru/cli.py

@@ -16,18 +16,19 @@ def main():
         "-r",
         "--requirement",
         type=str,
-        default="requirements.txt",
+        default=None,
         help=(
             "Path to the requirements file. Defaults to using requirements.txt from "
-            "the current directory if it exists."
+            "the current directory if it exists. Use '.' to indicate no requirements "
+            "file."
         ),
     )
     parser.add_argument(
         "-o",
         "--output",
         type=str,
         help=(
-            "Output updated packages to this file. Defaults to overwriting the input"
+            "Output updated packages to this file. Defaults to overwriting the input "
             "requirements file."
         ),
     )

src/pru/core.py

@@ -10,7 +10,9 @@
     import pkg_resources
 
 
-def read_requirements(requirements_path):
+def read_requirements(requirements_path=None):
+    if requirements_path is None:
+        requirements_path = get_requirements_path()
     with open(requirements_path, "r") as f:
         requirements = f.readlines()
 
@@ -56,7 +58,7 @@ def get_installed_packages_name_and_version():
     return packages
 
 
-def get_requirements_packages_name(requirements_path):
+def get_requirements_packages_name(requirements_path=None):
     requirements = read_requirements(requirements_path)
 
     package_names = []
@@ -67,14 +69,14 @@ def get_requirements_packages_name(requirements_path):
     return package_names
 
 
-def get_installed_requirements_packages_and_version(requirements_path):
+def get_installed_requirements_packages_and_version(requirements_path=None):
     packages = {}
     for package_name in get_requirements_packages_name(requirements_path):
         packages[package_name] = get_package_version(package_name)
     return packages
 
 
-def replace_requirements_packages_versions(requirements_path, output_path=None):
+def replace_requirements_packages_versions(requirements_path=None, output_path=None):
     requirements = read_requirements(requirements_path)
 
     installed_packages_name = get_installed_packages_name()
@@ -99,6 +101,8 @@ def replace_requirements_packages_versions(requirements_path, output_path=None):
             updated_requirements.append(requirement)
 
     if output_path is None:
+        if requirements_path is None:
+            requirements_path = get_requirements_path()
         output_path = requirements_path
 
     with open(output_path, "w") as f:
@@ -113,15 +117,21 @@ def verbose_subprocess(command):
             print(line.rstrip().decode("utf-8"))
 
 
-def upgrade_installed(requirements_path, command="pip install --upgrade --user"):
+def upgrade_installed(requirements_path=None, command="pip install --upgrade --user"):
     verbose_subprocess(
         f"{command} {' '.join(get_requirements_packages_name(requirements_path))}"
     )
 
 
 def upgrade_requirements(
-    requirements_path, output_path=None, command="pip install --upgrade --user"
+    requirements_path=None, output_path=None, command="pip install --upgrade --user"
 ):
     package_names = get_requirements_packages_name(requirements_path)
     verbose_subprocess(f"{command} {' '.join(package_names)}")
     replace_requirements_packages_versions(requirements_path, output_path)
+
+
+def get_requirements_path():
+    # TODO: support finding requirements file
+    requirements_path = "requirements.txt"
+    return requirements_path