[electrum] use the docker-compose command for functional tests

Summary: As of pytest-docker 2.0.0, docker-compose is no longer the default command. The default `docker compose` command now requires a newer version of `docker` than what is packaged for debian, so add a `docker_compose_command` pytest fixture to switch back to the previous behavior.

Test Plan: `@bot electrum-functional-tests`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14291

electrumabc/tests/regtest/test_rpc_misc.py

@@ -4,12 +4,13 @@
 from jsonrpcclient import request
 
 # See https://docs.pytest.org/en/7.1.x/how-to/fixtures.html
-from .util import docker_compose_file  # noqa: F401
-from .util import fulcrum_service  # noqa: F401
-from .util import (
+from .util import (  # noqa: F401
     EC_DAEMON_RPC_URL,
     SUPPORTED_PLATFORM,
     bitcoind_rpc_connection,
+    docker_compose_command,
+    docker_compose_file,
+    fulcrum_service,
     poll_for_answer,
 )
 

electrumabc/tests/regtest/test_rpc_payment_request.py

@@ -4,12 +4,13 @@
 from jsonrpcclient import request
 
 # See https://docs.pytest.org/en/7.1.x/how-to/fixtures.html
-from .util import docker_compose_file  # noqa: F401
-from .util import fulcrum_service  # noqa: F401
-from .util import (
+from .util import (  # noqa: F401
     EC_DAEMON_RPC_URL,
     SUPPORTED_PLATFORM,
     bitcoind_rpc_connection,
+    docker_compose_command,
+    docker_compose_file,
+    fulcrum_service,
     poll_for_answer,
 )
 

electrumabc/tests/regtest/util.py

@@ -149,6 +149,16 @@ def docker_compose_file(pytestconfig) -> str:
     )
 
 
+@pytest.fixture(scope="session")
+def docker_compose_command() -> str:
+    """Use the docker-compose command rather than `docker compose`. This is no longer
+    the default since pytest-docker 2.0.0 was released, so we need to specify it.
+    The docker version installed on CI seems to be too old to be compatible with the
+    way pytest-docker calls the `docker compose` command.
+    """
+    return "docker-compose"
+
+
 def make_electrum_data_dir():
     """Create a temporary directory with a regtest subdirectory, and copy the Electrum
     config file into it.