Added option to get resolved packages in a requirements.txt file. Fixes #135

src/python_inspector/resolve_cli.py

@@ -16,6 +16,7 @@
 from python_inspector import utils_pypi
 from python_inspector.cli_utils import FileOptionType
 from python_inspector.utils import write_output_in_file
+from python_inspector.utils import write_resolved_packages
 
 TRACE = False
 
@@ -115,6 +116,15 @@ def print_version(ctx, param, value):
     help="Write output as pretty-printed JSON to FILE as a tree in the style of pipdeptree. "
     "Use the special '-' file name to print results on screen/stdout.",
 )
+@click.option(
+    "--resolved-output",
+    "resolved_output",
+    type=FileOptionType(mode="w", encoding="utf-8", lazy=True),
+    required=False,
+    metavar="FILE",
+    help="Write the packages that are resolved after inspecting, into a TEXT file."
+    "The packages are written in a typical requirements file format that can be used by pip.",
+)
 @click.option(
     "-n",
     "--netrc",
@@ -194,6 +204,7 @@ def resolve_dependencies(
     index_urls,
     json_output,
     pdt_output,
+    resolved_output,
     netrc_file,
     max_rounds,
     use_cached_index=False,
@@ -285,6 +296,8 @@ def resolve_dependencies(
             output=output,
             location=json_output or pdt_output,
         )
+        if resolved_output:
+            write_resolved_packages(files, resolved_output)
     except Exception:
         import traceback
 

src/python_inspector/utils.py

@@ -54,6 +54,20 @@ def write_output_in_file(output, location):
     return output
 
 
+def write_resolved_packages(package_list, requirements_file):
+    """
+    Write the resolved package names and versions into ``requirements_file_path``
+    """
+    dependencies = package_list[0]["package_data"][0]["dependencies"]
+    resolved_packages = []
+    for dependency in dependencies:
+        if dependency["is_resolved"]:
+            package = dependency["extracted_requirement"]
+            resolved_packages.append(package)
+    for package in resolved_packages:
+        requirements_file.write(package + "\n")
+
+
 class Candidate(NamedTuple):
     """
     A candidate is a package that can be installed.

tests/data/resolved-pinned-requirements-expected.txt

@@ -0,0 +1,28 @@
+aboutcode-toolkit==7.0.2
+attrs==21.4.0
+beautifulsoup4==4.11.1
+certifi==2022.5.18.1
+charset-normalizer==2.0.12
+click==8.0.4
+colorama==0.4.4
+commoncode==30.2.0
+dparse2==0.6.1
+idna==3.3
+importlib-metadata==4.8.3
+intbitset==3.0.1
+packageurl-python==0.9.9
+packaging==21.3
+pip-requirements-parser==31.2.0
+pkginfo2==30.0.0
+pyparsing==3.0.9
+PyYAML==6.0
+requests==2.27.1
+resolvelib==0.8.1
+saneyaml==0.5.2
+soupsieve==2.3.2.post1
+text-unidecode==1.3
+toml==0.10.2
+typing==3.6.6
+typing_extensions==4.1.1
+urllib3==1.26.9
+zipp==3.6.0

tests/test_cli.py

@@ -444,6 +444,52 @@ def test_passing_of_unsupported_os():
         assert message in result.output
 
 
+@pytest.mark.online
+def test_resolved_cli():
+    """
+    Tests the '--resolved-output' option of resolve_dependencies() function.
+    The '--resolved-output' option takes in a filename and writes.
+    The resolved package dependencies into a .txt file with the given filename.
+    """
+    requirements_file = test_env.get_test_loc("pinned-requirements.txt")
+    expected_file = test_env.get_test_loc(
+        "resolved-pinned-requirements-expected.txt", must_exist=False
+    )
+    result_txt_file = test_env.get_temp_file("txt")
+    result_json_file = test_env.get_temp_file("json")
+    options = [
+        "--requirement",
+        requirements_file,
+        "--resolved-output",
+        result_txt_file,
+        "--json",
+        result_json_file,
+    ]
+    run_cli(options=options)
+    check_resolved_packages_results(result_txt_file, expected_file)
+
+
+def check_resolved_packages_results(result_file, expected_file, regen=REGEN_TEST_FIXTURES):
+    """
+    Check the ``result_file`` data against the ``expected_file`` expected results.
+
+    If ``regen`` is True the expected_file WILL BE overwritten with the new
+    results from ``results_file``. This is convenient for updating tests
+    expectations.
+    """
+    with open(result_file, "r") as res_file:
+        results = res_file.readlines()
+
+    if regen:
+        with open(expected_file, "w") as exo:
+            exo.writelines(results)
+        expected = results
+    else:
+        with open(expected_file) as reso:
+            expected = reso.readlines()
+    assert results == expected
+
+
 def check_requirements_resolution(
     requirements_file,
     expected_file,