Optimize experimental_python_types and add type-mapping tests

Instead of checking the type for each row, check the type once for each
fetch() call and compute a list of lambdas which are to be applied to
the values from each row. A new RowMapperFactory class is created to
wrap this behavior.
The experimental_python_types flag is now processed in the TrinoQuery
class instead of the TrinoResult class.

Type mapping tests for each lambda which maps rows to Python types is
added.

Author: lpoulain

.github/workflows/ci.yml

@@ -14,21 +14,6 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  checks:
-    runs-on: ubuntu-latest
-    steps:
-      - name: "Checkout the source code"
-        uses: actions/checkout@v2
-
-      - name: "Install Python"
-        uses: actions/setup-python@v2
-
-      - name: "Install pre-commit"
-        run: pip install pre-commit
-
-      - name: "Run pre-commit checks"
-        run: pre-commit run --all-files
-
   build:
     runs-on: ubuntu-latest
     strategy:
@@ -49,6 +34,7 @@ jobs:
           # Test with older Trino versions for backward compatibility
           - { python: "3.10", trino: "351" }  # first Trino version
     env:
+      TOX_PARALLEL_NO_SPINNER: 1
       TRINO_VERSION: "${{ matrix.trino }}"
     steps:
       - uses: actions/checkout@v2
@@ -59,7 +45,8 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install libkrb5-dev
-          pip install .[tests]
-      - name: Run tests
+          sudo curl -sSL https://install.python-poetry.org | python3
+          poetry install
+      - name: Run tox
         run: |
-          pytest -s tests/
+          poetry run tox --parallel

README.md

@@ -383,12 +383,12 @@ exits the *with* context and the queries succeed, otherwise
 
 ## Improved Python types
 
-If you enable the flag `experimental_python_types`, the client will convert the results of the query to the 
+If you enable the flag `experimental_python_types`, the client will convert the results of the query to the
 corresponding Python types. For example, if the query returns a `DECIMAL` column, the result will be a `Decimal` object.
 
-Limitations of the Python types are described in the 
-[Python types documentation](https://docs.python.org/3/library/datatypes.html). These limitations will generate an 
-exception `trino.exceptions.DataError` if the query returns a value that cannot be converted to the corresponding Python 
+Limitations of the Python types are described in the
+[Python types documentation](https://docs.python.org/3/library/datatypes.html). These limitations will generate an
+exception `trino.exceptions.DataError` if the query returns a value that cannot be converted to the corresponding Python
 type.
 
 ```python
@@ -418,6 +418,7 @@ assert cur.description[0][1] == "timestamp with time zone"
 
 Start by forking the repository and then modify the code in your fork.
 
+<<<<<<< HEAD
 We recommend that you use Python3's `venv` for development:
 
 ```
@@ -430,6 +431,16 @@ With `-e` passed to `pip install` above pip can reference the code you are
 modifying in the *virtual env*. That way, you do not need to run `pip install`
 again to make your changes applied to the *virtual env*.
 
+=======
+Clone the repository and go inside the code directory.
+
+Python dependencies are managed using [Poetry](https://python-poetry.org/) which helps to ensure the project is managed in a deterministic way. Poetry [creates a virtual environment](https://python-poetry.org/docs/managing-environments/) to aid with the process. Poetry should be installed via:
+
+```
+$ curl -sSL https://install.python-poetry.org | python3
+```
+
+>>>>>>> 1226d39 ([CI] Migrate to pyproject.toml and poetry for deterministic builds)
 When the code is ready, submit a Pull Request.
 
 ### Code style
@@ -443,25 +454,37 @@ Most of them also apply to code in trino-python-client.
 
 ### Running tests
 
-`trino-python-client` uses [pytest](https://pytest.org/) for its tests. To run
+`trino-python-client` uses [tox](https://tox.wiki/en/latest/)—a tool for standardizing testing in Python—which leverages the [pytest](https://pytest.org/) testing framework. To run
 only unit tests, type:
 
 ```
-$ pytest tests/unit
+$ poetry run tox -e <environment> -- tests/unit
 ```
 
+Similarly to run only integration tests, type:
+
+```
+$ poetry run tox -e <environment> -- tests/integration
+```
+
+where `<environment>` denotes the Python environment (see the configuration in `tox.ini`).
+
 Then you can pass options like `--pdb` or anything supported by `pytest --help`.
 
+<<<<<<< HEAD
 To run integration tests:
 
 ```
 $ pytest tests/integration
 ```
 
+=======
+>>>>>>> 1226d39 ([CI] Migrate to pyproject.toml and poetry for deterministic builds)
 They pull a Docker image and then run a container with a Trino server:
 - the image is named `trinodb/trino:${TRINO_VERSION}`
 - the container is named `trino-python-client-tests-{uuid4()[:7]}`
 
+<<<<<<< HEAD
 To run the tests with different versions of Python in managed *virtual envs*,
 use `tox` (see the configuration in `tox.ini`):
 
@@ -470,13 +493,30 @@ $ tox
 ```
 
 ## Releasing
+=======
+### pre-commit
+
+`trino-python-client` leverages [pre-commit](https://pre-commit.com/) to help identify simple issues before submission to code review. Checks include the validity of the `pyproject.toml` file, type checks via [Mypy](https://github.com/python/mypy), etc. To enable `pre-commit` run:
+
+```
+poetry run pre-commit install
+```
+
+which will run on every commit.  You can also run it anytime using:
+
+```
+poetry run tox -e pre-commit
+```
+
+### Releasing
+>>>>>>> 1226d39 ([CI] Migrate to pyproject.toml and poetry for deterministic builds)
 
 - [Set up your development environment](#Getting-Started-With-Development).
 - Check the local workspace is up to date and has no uncommitted changes
   ```bash
   git fetch -a && git status
   ```
-- Change version in `trino/__init__.py` to a new version, e.g. `0.123.0`.
+- Change version in `trino/pyproject.toml` to a new version, e.g. `0.123.0`.
 - Commit
   ```bash
   git commit -a -m "Bump version to 0.123.0"
@@ -487,12 +527,17 @@ $ tox
   ```
 - Create release package and upload it to PyPI
   ```bash
+<<<<<<< HEAD
   . .venv/bin/activate && \
   pip install twine && \
   rm -rf dist/ && \
   ./setup.py sdist bdist_wheel && \
   twine upload dist/* && \
   open https://pypi.org/project/trino/ && \
+=======
+  poetry publish --build &&
+  open https://pypi.org/project/trino/ &&
+>>>>>>> 1226d39 ([CI] Migrate to pyproject.toml and poetry for deterministic builds)
   echo "Released!"
   ```
 - Push the branch and the tag