Improve readability

cratedb_toolkit/testing/testcontainers/cratedb.py

@@ -91,7 +91,7 @@ def __init__(
 
         self._name = "testcontainers-cratedb"
 
-        cmd_opts = cmd_opts if cmd_opts else {}
+        cmd_opts = cmd_opts or {}
         self._command = self._build_cmd({**self.CMD_OPTS, **cmd_opts})
 
         self.CRATEDB_USER = user or self.CRATEDB_USER
@@ -110,7 +110,7 @@ def _build_cmd(opts: dict) -> str:
         for key, val in opts.items():
             if isinstance(val, bool):
                 val = str(val).lower()
-            cmd.append("-C{}={}".format(key, val))
+            cmd.append(f"-C{key}={val}")
         return " ".join(cmd)
 
     def _configure_ports(self) -> None:

tests/testing/test_testcontainers.py

@@ -0,0 +1,33 @@
+import pytest
+
+from cratedb_toolkit.testing.testcontainers.cratedb import CrateDBContainer
+
+
+@pytest.mark.parametrize(
+    "opts, expected",
+    [
+        pytest.param(
+            {"indices.breaker.total.limit": "90%"},
+            (
+                "-Cdiscovery.type=single-node "
+                "-Cnode.attr.storage=hot "
+                "-Cpath.repo=/tmp/snapshots "
+                "-Cindices.breaker.total.limit=90%"
+            ),
+            id="add_cmd_option",
+        ),
+        pytest.param(
+            {"discovery.type": "zen", "indices.breaker.total.limit": "90%"},
+            (
+                "-Cdiscovery.type=zen "
+                "-Cnode.attr.storage=hot "
+                "-Cpath.repo=/tmp/snapshots "
+                "-Cindices.breaker.total.limit=90%"
+            ),
+            id="override_defaults",
+        ),
+    ],
+)
+def test_build_command(opts, expected):
+    db = CrateDBContainer(cmd_opts=opts)
+    assert db._command == expected