Added testing stage and development stage as well as first tests

.gitlab-ci.yml

 ## Stage names in the pipeline.
 stages:
   - build
+  - test
+  - deploy
 
 variables:
   ## Name for the generated image. Change this if you wish, but watch out
   ## for special characters and spaces!
-  DOCKER_IMAGE_NAME: ${DOCKER_REGISTRY}/tjts5901
-  DOCKER_TAG: latest
+  DOCKER_IMAGE_NAME: ${DOCKER_REGISTRY}/tjts5901TeamFrozen
+  DOCKER_TAG: $CI_COMMIT_REF_SLUG
 
   ## (Optional) More verbose output from pipeline. Enabling it might reveal secrets.
   #CI_DEBUG_TRACE: "true"
@@ -43,3 +45,27 @@ build:
           --local dockerfile=. \
           --opt build-arg:CI_COMMIT_SHA=${CI_COMMIT_SHA} \
           --output type=image,name=${DOCKER_IMAGE_NAME}:${DOCKER_TAG},push=true
+        
+## Run the tests. If any of the tests fails, pipeline is rejected.         
+test:
+    ## Optional: include stage and environment name
+    stage: test
+    # environment: testing
+    image: ${DOCKER_IMAGE_NAME}:${DOCKER_TAG}
+    script:
+        - pip install --disable-pip-version-check -e .[test]
+        - pytest -v
+        - echo "Test were run succesfully!"
+
+## Deploy latest image to the production
+deploy:
+  stage: deploy
+  environment: production
+  image: docker:stable
+  only:
+    - main
+  script:
+    ## Copy credentials to container
+    - mkdir -p ${HOME}/.docker && echo "${DOCKER_AUTH_CONFIG}" > "${HOME}/.docker/config.json"
+    ## Add the `latest` tag to the image we have build.
+    - docker buildx imagetools create ${DOCKER_IMAGE_NAME}:${DOCKER_TAG} --tag ${DOCKER_IMAGE_NAME}:latest

tests/conftests.py

+import pytest
+from flask import Flask
+
+from tjts5901.app import create_app
+
+
+@pytest.fixture
+def app():
+    """
+    Application fixture.
+
+    Every test that requires `app` as parameter can use this fixture.
+
+    Example:
+    >>> def test_mytest(app: Flask):
+    >>>     ...
+    """
+    flask_app = create_app({
+        'TESTING': True,
+        'DEBUG': False,
+
+        # We need to set SERVER_NAME and PREFERRED_URL_SCHEME for testing.
+        'SERVER_NAME': 'localhost.localdomain',
+        'PREFERRED_URL_SCHEME': 'http',
+    })
+
+    # If you have done ties4080 course and have used Flask-WTF, you might
+    # have noticed that CSRF protection is enabled by default. This is
+    # problematic for testing, because we don't have a browser to generate
+    # CSRF tokens. We can disable CSRF protection for testing, but we need
+    # to make sure that we don't have CSRF protection enabled in production.
+
+    # flask_app.config['WTF_CSRF_ENABLED'] = False
+    # flask_app.config['WTF_CSRF_METHODS'] = []
+    # flask_app.config['WTF_CSRF_CHECK_DEFAULT'] = False
+
+    flask_app.testing = True
+    yield flask_app
+
+    # Do some cleanup here if needed.
+    ...
+
+
+@pytest.fixture
+def client(app):
+    return app.test_client()