feat(compose): ability to retain volumes when using context manager (#659)

# changes

On fiddling with a local project of mine, I realised we default to
removing volumes when using compose.
This is neat, but the context manager should also allow control over the
volumes kept.

This change adds the `keep_volumes` flag and hooks into `self.stop()`
that already had the option.

I added a test to cover the new functionality :

Author: totallyzen

core/testcontainers/compose/compose.py

@@ -165,6 +165,7 @@ class DockerCompose:
     pull: bool = False
     build: bool = False
     wait: bool = True
+    keep_volumes: bool = False
     env_file: Optional[str] = None
     services: Optional[list[str]] = None
     docker_command_path: Optional[str] = None
@@ -178,7 +179,7 @@ def __enter__(self) -> "DockerCompose":
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb) -> None:
-        self.stop()
+        self.stop(not self.keep_volumes)
 
     def docker_compose_command(self) -> list[str]:
         """

core/tests/compose_fixtures/basic_volume/docker-compose.yaml

@@ -0,0 +1,17 @@
+services:
+  alpine:
+    image: alpine:latest
+    init: true
+    command:
+      - sh
+      - -c
+      - 'while true; do sleep 0.1 ; date -Ins; done'
+    read_only: true
+    volumes:
+      - type: volume
+        source: my-data
+        target: /var/lib/example/data
+        read_only: false
+
+volumes:
+  my-data: {}

core/tests/test_compose.py

@@ -1,3 +1,4 @@
+import subprocess
 from pathlib import Path
 from re import split
 from time import sleep
@@ -147,6 +148,27 @@ def test_compose_logs():
         assert not line or container.Service in next(iter(line.split("|")), None)
 
 
+def test_compose_volumes():
+    _file_in_volume = "/var/lib/example/data/hello"
+    volumes = DockerCompose(context=FIXTURES / "basic_volume", keep_volumes=True)
+    with volumes:
+        stdout, stderr, exitcode = volumes.exec_in_container(
+            ["/bin/sh", "-c", f"echo hello > {_file_in_volume}"], "alpine"
+        )
+    assert exitcode == 0
+
+    # execute another time to confirm the file is still there, but we're not keeping the volumes this time
+    volumes.keep_volumes = False
+    with volumes:
+        stdout, stderr, exitcode = volumes.exec_in_container(["cat", _file_in_volume], "alpine")
+    assert exitcode == 0
+    assert "hello" in stdout
+
+    # third time we expect the file to be missing
+    with volumes, pytest.raises(subprocess.CalledProcessError):
+        volumes.exec_in_container(["cat", _file_in_volume], "alpine")
+
+
 # noinspection HttpUrlsUsage
 def test_compose_ports():
     # fairly straight forward - can we get the right port to request it