Pin aiida-core version (#440)

Prevent Apps from messing with aiida-core installation.
If users need to use a specific AiiDA version, they should use
the corresponding AiiDAlab image.

stack/base/Dockerfile

@@ -16,11 +16,12 @@ WORKDIR /opt/
 
 ARG AIIDA_VERSION
 
-# Pin shared requirements in the base environemnt.
-# The lower bound of aiida-core is set to the version of aiida-core to prevent
-# lower aiida-core DB version installed and trigger database downgrade.
+# Pin shared requirements in the base environment.
+# We pin aiida-core to the exact installed version,
+# to prevent accidental upgrade or downgrade, that might
+# induce DB migration or break shared dependencies of AiiDAlab Apps.
 RUN echo "pip==23.3.1" > /opt/requirements.txt && \
-     echo "aiida-core>=${AIIDA_VERSION},<3" >> /opt/requirements.txt
+  echo "aiida-core==${AIIDA_VERSION}" >> /opt/requirements.txt
 
 # Install the shared requirements.
 RUN mamba install --yes \

tests/test-base.py

@@ -5,13 +5,13 @@
 from packaging.version import parse
 
 
-@pytest.mark.parametrize("incompatible_version", ["1.6.3"])
+@pytest.mark.parametrize("incompatible_version", ["2.3.0"])
 def test_prevent_pip_install_of_incompatible_aiida_version(
     aiidalab_exec, nb_user, aiida_version, incompatible_version
 ):
     package_manager = "pip"
     assert parse(aiida_version) != parse(incompatible_version)
-    # Expected to succeed:
+    # Expected to succeed, although should be a no-op.
     aiidalab_exec(
         f"{package_manager} install aiida-core=={aiida_version}", user=nb_user
     )