diff --git a/pyinfra/config.py b/pyinfra/config.py
index 1e94f08..06c9cae 100644
--- a/pyinfra/config.py
+++ b/pyinfra/config.py
@@ -1,5 +1,6 @@
 """Implements a config object with dot-indexing syntax."""
 
+
 from envyaml import EnvYAML
 
 from pyinfra.locations import CONFIG_FILE
@@ -17,9 +18,6 @@ class DotIndexable:
     def __getattr__(self, item):
         return _get_item_and_maybe_make_dotindexable(self.x, item)
 
-    def __setitem__(self, key, value):
-        self.x[key] = value
-
     def __repr__(self):
         return self.x.__repr__()
 
diff --git a/pyinfra/test/unit_tests/config_test.py b/pyinfra/test/unit_tests/config_test.py
new file mode 100644
index 0000000..ed0620b
--- /dev/null
+++ b/pyinfra/test/unit_tests/config_test.py
@@ -0,0 +1,38 @@
+import tempfile
+
+import pytest
+import yaml
+
+from pyinfra.config import Config
+
+
+@pytest.fixture
+def config_file_content():
+    return {"A": [{"B": [1, 2]}, {"C": 3}, 4], "D": {"E": {"F": True}}}
+
+
+@pytest.fixture
+def config(config_file_content):
+    with tempfile.NamedTemporaryFile(suffix=".yaml", mode="w") as f:
+        yaml.dump(config_file_content, f, default_flow_style=False)
+        yield Config(f.name)
+
+
+def test_dot_access_key_exists(config):
+    assert config.A == [{"B": [1, 2]}, {"C": 3}, 4]
+    assert config.D.E["F"]
+
+
+def test_access_key_exists(config):
+    assert config["A"] == [{"B": [1, 2]}, {"C": 3}, 4]
+    assert config["A"][0] == {"B": [1, 2]}
+    assert config["A"][0]["B"] == [1, 2]
+    assert config["A"][0]["B"][0] == 1
+
+
+def test_dot_access_key_does_not_exists(config):
+    assert config.B is None
+
+
+def test_access_key_does_not_exists(config):
+    assert config["B"] is None
diff --git a/run_tests.sh b/run_tests.sh
index e245822..8a5a58f 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -1,11 +1,9 @@
 echo "${bamboo_nexus_password}" | docker login --username "${bamboo_nexus_user}" --password-stdin nexus.iqser.com:5001
-docker build -f Dockerfile_tests -t pyinfra-tests:dev .
-docker tag pyinfra-tests:dev nexus.iqser.com:5001/red/pyinfra-tests:dev
-docker push nexus.iqser.com:5001/red/pyinfra-tests:dev
+docker build -f Dockerfile_tests -t pyinfra-tests .
 
 rnd=$(date +"%s")
 name=pyinfra-tests-${rnd}
 
 echo "running tests container"
 
-docker run --rm --net=host --name $name -v $PWD:$PWD -w $PWD -v /var/run/docker.sock:/var/run/docker.sock pyinfra-tests:dev
+docker run --rm --net=host --name $name -v $PWD:$PWD -w $PWD -v /var/run/docker.sock:/var/run/docker.sock pyinfra-tests