Require requirements (#680)

* enforce requirements.txt existing

---------

Co-authored-by: Alessandro Molina <alessandro.molina@posit.co>
Co-authored-by: Taylor Steinberg <taylor@steinberg.xyz>

Author: 3 people

rsconnect/environment.py

@@ -139,12 +139,13 @@ def create_python_environment(
             module_file = app_file
 
         _warn_on_ignored_manifest(directory)
-        _warn_if_no_requirements_file(directory, requirements_file)
         _warn_if_environment_directory(directory)
 
         python_version_requirement = pyproject.detect_python_version_requirement(directory)
         _warn_on_missing_python_version(python_version_requirement)
 
+        _check_requirements_file(directory, requirements_file)
+
         if python is not None:
             # TODO: Remove the option in a future release
             logger.warning(
@@ -317,9 +318,9 @@ def _warn_on_ignored_manifest(directory: str) -> None:
         )
 
 
-def _warn_if_no_requirements_file(directory: str, requirements_file: typing.Optional[str]) -> None:
+def _check_requirements_file(directory: str, requirements_file: typing.Optional[str]) -> None:
     """
-    Check that a requirements file exists, and that it lives inside the deployment directory.
+    Verify that a requirements file exists inside the deployment directory.
 
     :param directory: the directory to check in.
     :param requirements_file: the name of the requirements file, or None to skip the check.
@@ -336,10 +337,11 @@ def _warn_if_no_requirements_file(directory: str, requirements_file: typing.Opti
         )
 
     if not requirements_file_path.exists():
-        click.secho(
-            "    Warning: Capturing the environment using 'pip freeze'.\n"
-            "             Consider creating a %s file instead." % requirements_file,
-            fg="yellow",
+        raise RSConnectException(
+            "The requirements file '%s' does not exist in '%s'.\n"
+            "Please create the file or specify a different file with --requirements-file.\n"
+            "To have the requirements file generated using pip freeze, pass --force-generate."
+            % (requirements_file, directory)
         )
 
 

rsconnect/subprocesses/inspect_environment.py

@@ -74,11 +74,17 @@ def detect_environment(dirname: str, requirements_file: Optional[str] = "require
     """
 
     if requirements_file is None:
+        # --force-generate sets requirements_file to None
         result = pip_freeze()
     elif os.path.basename(requirements_file) == "uv.lock":
         result = uv_export(dirname, requirements_file)
     else:
-        result = output_file(dirname, requirements_file, "pip") or pip_freeze()
+        result = output_file(dirname, requirements_file, "pip")
+        if result is None:
+            raise EnvironmentException(
+                "The requirements file '%s' was not found in '%s'. "
+                "Please create it or use --force-generate to use pip freeze." % (requirements_file, dirname)
+            )
 
     if result is not None:
         result["python"] = get_python_version()

tests/test_bundle.py

@@ -154,7 +154,7 @@ def test_make_notebook_source_bundle2(self):
         # the test environment. Don't do this in the production code, which
         # runs in the notebook server. We need the introspection to run in
         # the kernel environment and not the notebook server environment.
-        environment = Environment.create_python_environment(directory)
+        environment = Environment.create_python_environment(directory, requirements_file=None)
 
         with make_notebook_source_bundle(
             nb_path,
@@ -314,7 +314,7 @@ def test_make_quarto_source_bundle_from_simple_project(self):
         # input file.
         create_fake_quarto_rendered_output(temp_proj, "myquarto")
 
-        environment = Environment.create_python_environment(temp_proj)
+        environment = Environment.create_python_environment(temp_proj, requirements_file=None)
 
         # mock the result of running of `quarto inspect <project_dir>`
         inspect = {
@@ -411,7 +411,7 @@ def test_make_quarto_source_bundle_from_complex_project(self):
         create_fake_quarto_rendered_output(site_dir, "index")
         create_fake_quarto_rendered_output(site_dir, "about")
 
-        environment = Environment.create_python_environment(temp_proj)
+        environment = Environment.create_python_environment(temp_proj, requirements_file=None)
 
         # mock the result of running of `quarto inspect <project_dir>`
         inspect = {

tests/test_environment.py

@@ -11,6 +11,7 @@
 from rsconnect.exception import RSConnectException
 from rsconnect.environment import Environment, which_python
 from rsconnect.subprocesses.inspect_environment import (
+    EnvironmentException,
     detect_environment,
     filter_pip_freeze_output,
     get_default_locale,
@@ -83,7 +84,7 @@ def test_requirements_override(self):
             assert result.source == "file"
 
     def test_pip_freeze(self):
-        result = Environment.create_python_environment(get_dir("pip2"))
+        result = Environment.create_python_environment(get_dir("pip2"), requirements_file=None)
 
         # these are the dependencies declared in our pyproject.toml
         self.assertIn("six", result.contents)
@@ -223,22 +224,30 @@ def test_is_not_executable(self):
 
 class TestPythonVersionRequirements:
     def test_pyproject_toml(self):
-        env = Environment.create_python_environment(os.path.join(TESTDATA, "python-project", "using_pyproject"))
+        env = Environment.create_python_environment(
+            os.path.join(TESTDATA, "python-project", "using_pyproject"), requirements_file=None
+        )
         assert env.python_interpreter == sys.executable
         assert env.python_version_requirement == ">=3.8"
 
     def test_python_version(self):
-        env = Environment.create_python_environment(os.path.join(TESTDATA, "python-project", "using_pyversion"))
+        env = Environment.create_python_environment(
+            os.path.join(TESTDATA, "python-project", "using_pyversion"), requirements_file=None
+        )
         assert env.python_interpreter == sys.executable
         assert env.python_version_requirement == ">=3.8,<3.12"
 
     def test_all_of_them(self):
-        env = Environment.create_python_environment(os.path.join(TESTDATA, "python-project", "allofthem"))
+        env = Environment.create_python_environment(
+            os.path.join(TESTDATA, "python-project", "allofthem"), requirements_file=None
+        )
         assert env.python_interpreter == sys.executable
         assert env.python_version_requirement == ">=3.8,<3.12"
 
     def test_missing(self):
-        env = Environment.create_python_environment(os.path.join(TESTDATA, "python-project", "empty"))
+        env = Environment.create_python_environment(
+            os.path.join(TESTDATA, "python-project", "empty"), requirements_file=None
+        )
         assert env.python_interpreter == sys.executable
         assert env.python_version_requirement is None
 
@@ -393,3 +402,44 @@ def test_python_interpreter(self):
             "Please use a .python-version file to force a specific interpreter version."
         )
         assert result.python == current_python_version
+
+
+class TestRequirementsFileRequired:
+    """When a requirements file is requested (the default), it must exist.
+    When force-generate is used (requirements_file=None), pip freeze is used regardless."""
+
+    def test_requirements_requested_and_file_exists(self):
+        """Default behavior with requirements.txt present succeeds and reads the file."""
+        result = Environment.create_python_environment(get_dir("pip1"))
+        assert result.source == "file"
+        assert result.filename == "requirements.txt"
+
+    def test_requirements_requested_and_file_missing(self):
+        """Default behavior without requirements.txt raises an error."""
+        with pytest.raises(RSConnectException, match="does not exist"):
+            Environment.create_python_environment(get_dir("pip2"))
+
+    def test_force_generate_and_file_exists(self):
+        """Force-generate ignores the existing requirements.txt and uses pip freeze."""
+        result = Environment.create_python_environment(get_dir("pip1"), requirements_file=None)
+        assert result.source == "pip_freeze"
+
+    def test_force_generate_and_file_missing(self):
+        """Force-generate works even without requirements.txt."""
+        result = Environment.create_python_environment(get_dir("pip2"), requirements_file=None)
+        assert result.source == "pip_freeze"
+
+    def test_detect_environment_requires_file(self):
+        """Subprocess-level: detect_environment errors when the file is missing."""
+        with pytest.raises(EnvironmentException, match="was not found"):
+            detect_environment(get_dir("pip2"), requirements_file="requirements.txt")
+
+    def test_detect_environment_reads_file(self):
+        """Subprocess-level: detect_environment reads the file when present."""
+        result = detect_environment(get_dir("pip1"), requirements_file="requirements.txt")
+        assert result.source == "file"
+
+    def test_detect_environment_force_generate(self):
+        """Subprocess-level: detect_environment uses pip freeze when requirements_file=None."""
+        result = detect_environment(get_dir("pip2"), requirements_file=None)
+        assert result.source == "pip_freeze"