Migrate testing from pytest-dockerc to using python-on-whales

The pytest-dockerc plug is unmaintained and there is now a dependency
issues with PyYAML because of the release of Cython v3 (which is itself
a build dependency for PyYAML). After some research this seemed like
the most similar package in terms of functionality to the package we
are replacing. Although it is not a pytest plugin it still provides
similar access and uses the Docker composition defined in the
repository.

requirements-test.txt

@@ -1,4 +1,4 @@
 --requirement requirements.txt
 pre-commit
 pytest
-pytest-dockerc
+python-on-whales

tests/conftest.py

@@ -4,16 +4,26 @@
 """
 # Third-Party Libraries
 import pytest
+from python_on_whales import docker
 
 MAIN_SERVICE_NAME = "example"
 VERSION_SERVICE_NAME = f"{MAIN_SERVICE_NAME}-version"
 
 
+@pytest.fixture(scope="session")
+def dockerc():
+    """Start up the Docker composition."""
+    docker.compose.up(detach=True)
+    yield docker
+    docker.compose.down()
+
+
 @pytest.fixture(scope="session")
 def main_container(dockerc):
     """Return the main container from the Docker composition."""
-    # find the container by name even if it is stopped already
-    return dockerc.containers(service_names=[MAIN_SERVICE_NAME], stopped=True)[0]
+    # Find the container by name even if it is stopped already.
+    # Note: There should only be a single container returned
+    return dockerc.compose.ps(services=[MAIN_SERVICE_NAME], all=True)[0]
 
 
 @pytest.fixture(scope="session")
@@ -22,8 +32,9 @@ def version_container(dockerc):
 
     The version container should just output the version of its underlying contents.
     """
-    # find the container by name even if it is stopped already
-    return dockerc.containers(service_names=[VERSION_SERVICE_NAME], stopped=True)[0]
+    # Find the container by name even if it is stopped already.
+    # Note: There should only be a single container returned
+    return dockerc.compose.ps(services=[VERSION_SERVICE_NAME], all=True)[0]
 
 
 def pytest_addoption(parser):

tests/container_test.py

@@ -22,15 +22,15 @@ def test_container_count(dockerc):
     """Verify the test composition and container."""
     # stopped parameter allows non-running containers in results
     assert (
-        len(dockerc.containers(stopped=True)) == 2
+        len(dockerc.compose.ps(all=True)) == 2
     ), "Wrong number of containers were started."
 
 
 def test_wait_for_ready(main_container):
     """Wait for container to be ready."""
     TIMEOUT = 10
     for i in range(TIMEOUT):
-        if READY_MESSAGE in main_container.logs().decode("utf-8"):
+        if READY_MESSAGE in main_container.logs():
             break
         time.sleep(1)
     else:
@@ -42,16 +42,46 @@ def test_wait_for_ready(main_container):
 
 def test_wait_for_exits(main_container, version_container):
     """Wait for containers to exit."""
-    assert main_container.wait() == 0, "Container service (main) did not exit cleanly"
+    TIMEOUT = 30
+    ELAPSED = 0
+    for i in range(TIMEOUT):
+        if main_container.state.status == "exited":
+            break
+        time.sleep(1)
+        ELAPSED += 1
+    else:
+        raise Exception(
+            f"Container service (main) did not exit within {TIMEOUT} seconds."
+        )
+    for i in range(TIMEOUT - ELAPSED):
+        if version_container.state.status == "exited":
+            break
+        time.sleep(1)
+    else:
+        raise Exception(
+            f"Container service (version) did not exit within {TIMEOUT} seconds."
+        )
+    assert (
+        main_container.state.exit_code == 0
+    ), "Container service (main) did not exit cleanly"
     assert (
-        version_container.wait() == 0
+        version_container.state.exit_code == 0
     ), "Container service (version) did not exit cleanly"
 
 
 def test_output(main_container):
     """Verify the container had the correct output."""
-    main_container.wait()  # make sure container exited if running test isolated
-    log_output = main_container.logs().decode("utf-8")
+    # make sure container exited if running test isolated
+    TIMEOUT = 30
+    for i in range(TIMEOUT):
+        if main_container.state.status == "exited":
+            break
+        time.sleep(1)
+    else:
+        raise Exception(
+            f"Container service (main) did not exit within {TIMEOUT} seconds."
+        )
+    log_output = main_container.logs()
     assert SECRET_QUOTE in log_output, "Secret not found in log output."
 
 
@@ -71,8 +101,17 @@ def test_release_version():
 
 def test_log_version(version_container):
     """Verify the container outputs the correct version to the logs."""
-    version_container.wait()  # make sure container exited if running test isolated
-    log_output = version_container.logs().decode("utf-8").strip()
+    # make sure container exited if running test isolated
+    TIMEOUT = 30
+    for i in range(TIMEOUT):
+        if version_container.state.status == "exited":
+            break
+        time.sleep(1)
+    else:
+        raise Exception(
+            f"Container service (version) did not exit within {TIMEOUT} seconds."
+        )
+    log_output = version_container.logs().strip()
     pkg_vars = {}
     with open(VERSION_FILE) as f:
         exec(f.read(), pkg_vars)  # nosec
@@ -89,5 +128,6 @@ def test_container_version_label_matches(version_container):
         exec(f.read(), pkg_vars)  # nosec
     project_version = pkg_vars["__version__"]
     assert (
-        version_container.labels["org.opencontainers.image.version"] == project_version
+        version_container.config.labels["org.opencontainers.image.version"]
+        == project_version
     ), "Dockerfile version label does not match project version"