From 4644fcf11e114a643a35244d6605501bbfa002ec Mon Sep 17 00:00:00 2001
From: Maria Knorps <maria.knorps@gmail.com>
Date: Tue, 25 Jul 2023 11:33:50 +0200
Subject: [PATCH] ADD CLI option for --install-deps

---
 README.md                     |  2 ++
 fawltydeps/cli_parser.py      |  9 +++++++++
 tests/test_cmdline.py         | 24 ++++++++++++++++++++++++
 tests/test_cmdline_options.py |  2 +-
 tests/test_settings.py        |  2 +-
 5 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 8a375723..0d8bad9b 100644
--- a/README.md
+++ b/README.md
@@ -299,6 +299,8 @@ Here is a complete list of configuration directives we support:
   declared dependencies. Must be one of `"requirements.txt"`, `"setup.py"`,
   `"setup.cfg"`, `"pyproject.toml"`, or leave it unset (i.e. the default) for
   auto-detection (based on filename).
+- `install-deps`: Install Python dependencies gathered with FawltyDeps to
+  a temporary virtual environment. Dependencies will be installed from PyPI.
 - `verbosity`: An integer controlling the default log level of FawltyDeps:
   - `-2`: Only `CRITICAL`-level log messages are shown.
   - `-1`: `ERROR`-level log messages and above are shown.
diff --git a/fawltydeps/cli_parser.py b/fawltydeps/cli_parser.py
index 1ffffe5f..4ea49bc8 100644
--- a/fawltydeps/cli_parser.py
+++ b/fawltydeps/cli_parser.py
@@ -171,6 +171,15 @@ def populate_parser_paths_options(parser: argparse._ActionsContainer) -> None:
             " Python environment where FawltyDeps is installed."
         ),
     )
+    parser.add_argument(
+        "--install-deps",
+        dest="install_deps",
+        action="store_true",
+        help=(
+            "Allow FawltyDeps to `pip install` declared dependencies into a"
+            " separate temporary virtualenv to discover the imports they expose."
+        ),
+    )
     parser.add_argument(
         "--custom-mapping-file",
         nargs="+",
diff --git a/tests/test_cmdline.py b/tests/test_cmdline.py
index 3586bbee..0ff4991f 100644
--- a/tests/test_cmdline.py
+++ b/tests/test_cmdline.py
@@ -910,6 +910,30 @@ def test_cmdline_on_ignored_undeclared_option(
             ).splitlines(),
             id="generate_toml_config_with_multiple_pyenvs",
         ),
+        pytest.param(
+            {},
+            ["--install-deps", "--generate-toml-config"],
+            dedent(
+                """\
+                # Copy this TOML section into your pyproject.toml to configure FawltyDeps
+                # (default values are commented)
+                [tool.fawltydeps]
+                # actions = ['check_undeclared', 'check_unused']
+                # output_format = 'human_summary'
+                # code = ['.']
+                # deps = ['.']
+                # pyenvs = []
+                # ignore_undeclared = []
+                # ignore_unused = []
+                # deps_parser_choice = ...
+                install_deps = true
+                # verbosity = 0
+                # custom_mapping_file = []
+                # [tool.fawltydeps.custom_mapping]
+                """
+            ).splitlines(),
+            id="generate_toml_config_with_install_deps",
+        ),
     ],
 )
 def test_cmdline_args_in_combination_with_config_file(
diff --git a/tests/test_cmdline_options.py b/tests/test_cmdline_options.py
index 95a66417..f0b58d01 100644
--- a/tests/test_cmdline_options.py
+++ b/tests/test_cmdline_options.py
@@ -60,7 +60,7 @@
 """
 )
 venvs = [str(project_with_no_issues / ".venv")]
-other = ["--generate-toml-file", "--version"]
+other = ["--generate-toml-config", "--version", "--install-deps"]
 
 
 # Options below contain paths specific for an input project
diff --git a/tests/test_settings.py b/tests/test_settings.py
index c9ca26c8..905dad06 100644
--- a/tests/test_settings.py
+++ b/tests/test_settings.py
@@ -28,7 +28,6 @@
     code={Path(".")},
     deps={Path(".")},
     pyenvs=set(),
-    custom_mapping_file=set(),
     custom_mapping=None,
     output_format=OutputFormat.HUMAN_SUMMARY,
     ignore_undeclared=set(),
@@ -36,6 +35,7 @@
     deps_parser_choice=None,
     install_deps=False,
     verbosity=0,
+    custom_mapping_file=set(),
 )