feat: make pytest-testinfra optional

This removes the use of testinfra from the main codebase and the test suite
making it an optional dependency.

You can still use "connection.connection" to get testinfra's connection object
if you have it installed.

README.rst

@@ -21,8 +21,7 @@ Find the latest documentation on `dcermak.github.io/pytest_container
 <https://dcermak.github.io/pytest_container/>`_.
 
 ``pytest_container`` is a `pytest <https://pytest.org>`_ plugin
-to test container images via pytest fixtures and `testinfra
-<https://testinfra.readthedocs.io/en/latest/>`_. It takes care of all the boring
+to test container images via pytest fixtures. It takes care of all the boring
 tasks, like spinning up containers, finding free ports and cleaning up after
 tests, and allows you to focus on implementing the actual tests.
 
@@ -49,16 +48,24 @@ instantiating a ``Container`` and parametrizing a test function with the
 
    @pytest.mark.parametrize("container", [TW], indirect=["container"])
    def test_etc_os_release_present(container: ContainerData):
-       assert container.connection.file("/etc/os-release").exists
+        assert container.remote.check_output("test -f /etc/os-release")
 
 
 The fixture automatically pulls and spins up the container, stops it and removes
 it after the test is completed. Your test function receives an instance of
-``ContainerData`` with the ``ContainerData.connection`` attribute. The
-``ContainerData.connection`` attribute is a `testinfra
-<https://testinfra.readthedocs.io/en/latest/>`_ connection object. It can be
-used to run basic tests inside the container itself. For example, you can check
-whether files are present, packages are installed, etc.
+``ContainerData``.
+
+
+Testinfa
+--------
+
+You can optionally use the `testinfra <https://testinfra.readthedocs.io/en/latest/>`_
+library to interact with the container.  You need to install the ``pytest-testinfra``
+package directly or use the ``[testinfra]`` extra on this package.
+
+If test infra is installed, the ``ContainerData`` instance will have a
+``connection`` attribute that is an instance of ``testinfra.Connection``. Otherwise
+this attribute will be ``None``.
 
 
 Use cases

pyproject.toml

@@ -28,17 +28,22 @@ classifiers = [
 [tool.poetry.dependencies]
 python = ">=3.6.2,<4.0"
 pytest = ">= 3.10"
-pytest-testinfra = [
-    { version = ">=6.4.0", python = "< 3.7" },
-    { version = ">=7.0", python = ">= 3.7,< 3.8" },
-    { version = ">=8.0", python = ">= 3.8" }
-]
 dataclasses = { version = ">=0.8", python = "< 3.7" }
 typing-extensions = { version = ">=3.0", markers="python_version < '3.8'" }
 cached-property = { version = "^1.5", markers="python_version < '3.8'" }
 filelock = "^3.4"
 deprecation = "^2.1"
 
+pytest-testinfra = [
+    { version = ">=6.4.0", python = "< 3.7", optional = true },
+    { version = ">=7.0", python = ">= 3.7,< 3.8", optional = true },
+    { version = ">=8.0", python = ">= 3.8", optional = true }
+]
+
+
+[tool.poetry.extras]
+testinfra = ["pytest-testinfra"]
+
 [tool.poetry.dev-dependencies]
 black = ">=21.9b0"
 mypy = ">=0.942"
@@ -51,6 +56,8 @@ pytest-xdist = ">=2.4.0"
 Sphinx = ">=5.0"
 pytest-rerunfailures = ">=10.2"
 typeguard = ">=2.13"
+ifaddr = "^0.2.0"
+
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]

pytest_container/build.py

@@ -3,13 +3,13 @@
 builds via :py:class:`MultiStageBuild`.
 
 """
+import subprocess
 import tempfile
 from dataclasses import dataclass
 from os.path import basename
 from os.path import join
 from pathlib import Path
 from string import Template
-from subprocess import check_output
 from typing import Dict
 from typing import List
 from typing import Optional
@@ -156,10 +156,12 @@ def containerfile(self) -> str:
         """
         return Template(self.containerfile_template).substitute(
             **{
-                k: v
-                if isinstance(v, str)
-                else str(
-                    container_and_marks_from_pytest_param(v)[0]._build_tag
+                k: (
+                    v
+                    if isinstance(v, str)
+                    else str(
+                        container_and_marks_from_pytest_param(v)[0]._build_tag
+                    )
                 )
                 for k, v in self.containers.items()
             }
@@ -222,15 +224,18 @@ def run_build_step(
         # This is an ugly, duplication of the launcher code
         with tempfile.TemporaryDirectory() as tmp_dir:
             iidfile = join(tmp_dir, str(uuid4()))
-            cmd = (
-                runtime.build_command
-                + (extra_build_args or [])
-                + [f"--iidfile={iidfile}"]
-                + (["--target", target] if target else [])
-                + [str(tmp_path)]
-            )
+            cmd: List[str] = []
+            cmd.extend(runtime.build_command)
+            if extra_build_args:
+                cmd.extend(extra_build_args)
+            cmd.extend(["--iidfile", iidfile])
+            if target:
+                cmd.extend(["--target", target])
+            cmd.append(str(tmp_path))
             _logger.debug("Running multistage container build: %s", cmd)
-            check_output(cmd)
+            subprocess.check_call(
+                cmd, stdout=subprocess.DEVNULL, stderr=subprocess.PIPE
+            )
             return runtime.get_image_id_from_iidfile(iidfile)
 
     def build(

pytest_container/compat.py

@@ -0,0 +1,15 @@
+from typing import TYPE_CHECKING
+
+# mypy will try to import cached_property but fail to find its types
+# since we run mypy with the most recent python version, we can simply import
+# cached_property from stdlib and we'll be fine
+if TYPE_CHECKING:  # pragma: no cover
+    from functools import cached_property
+else:
+    try:
+        from functools import cached_property
+    except ImportError:
+        from cached_property import cached_property
+
+
+__all__ = ["cached_property"]