Use Conda environment for testing and cancel stale jobs

.github/workflows/python-tests.yml

@@ -6,6 +6,13 @@ on:
   pull_request:
     branches: [ main ]
 
+# Cancels all previous workflow runs for pull requests that have not completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name for pull requests
+  # or the commit hash for any other events.
+  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.head_ref || github.sha }}
+  cancel-in-progress: true
+
 jobs:
   changes:
     name: "Check for changes"
@@ -55,21 +62,43 @@ jobs:
     - uses: actions/checkout@v2
       with:
         fetch-depth: 0
+
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
+      uses: conda-incubator/setup-miniconda@v2
       with:
+        mamba-version: "*"
+        channels: conda-forge,defaults
+        channel-priority: true
         python-version: ${{ matrix.python-version }}
+        auto-update-conda: true
+
     - name: Install dependencies
+      shell: bash -l {0}
       run: |
-        python -m pip install --upgrade pip
+        mamba install --yes -q "python~=${PYTHON_VERSION}=*_cpython" theano-pymc mkl numpy scipy pip mkl-service
         if [[ "${{ matrix.pymc3-version }}" != "stable" ]]; then pip install "pymc3 @ git+https://github.com/pymc-devs/pymc3.git@master"; fi
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+        mamba list && pip freeze
+        python -c 'import theano; print(theano.config.__str__(print_doc=False))'
+        python -c 'import theano; assert(theano.config.blas__ldflags != "")'
+      env:
+        PYTHON_VERSION: ${{ matrix.python-version }}
+
     - name: Test with pytest
+      shell: bash -l {0}
       run: |
-        pytest tests --cov=pymc3_hmm --cov-report=xml:./coverage.xml
+        pytest -x -r A --verbose tests --cov=pymc3_hmm --cov-report=xml:./coverage.xml
+      env:
+        MKL_THREADING_LAYER: GNU
+        MKL_NUM_THREADS: 1
+        OMP_NUM_THREADS: 1
+
     - name: Fetch main for coverage diff
+      shell: bash -l {0}
       run: |
         git fetch --no-tags --prune origin main
+
     - name: Check coverage
+      shell: bash -l {0}
       run: |
         diff-cover ./coverage.xml --compare-branch=origin/main --fail-under=100 --diff-range-notation '..'