Use mamba + pytest-xdist to speed up CI testing

.github/workflows/climpred_testing.yml

@@ -6,32 +6,36 @@ jobs:
   test:  # Runs testing suite on various python versions.
     name: Test climpred, python ${{ matrix.python-version }}
     runs-on: ubuntu-latest
+    defaults:
+        run:
+          shell: bash -l {0}
     strategy:
+      fail-fast: false
       matrix:
         python-version: [3.6, 3.7, 3.8]
     steps:
       - uses: actions/checkout@v2
         with:
           ref: ${{github.event.pull_request.head.ref}}
           repository: ${{github.event.pull_request.head.repo.full_name}}
-      - name: Install Conda environment
+      - name: Set up conda
         uses: conda-incubator/setup-miniconda@v1
         with:
           auto-update-conda: true
+          channels: conda-forge
+          mamba-version: '*'
           activate-environment: climpred-minimum-tests
-          environment-file: ci/requirements/minimum-tests.yml
           python-version: ${{ matrix.python-version }}
+      - name: Set up conda environment
+        run: |
+          mamba env update -f ci/requirements/minimum-tests.yml
       - name: Conda info
-        shell: bash -l {0}
         run: conda info
       - name: Conda list
-        shell: bash -l {0}
         run: conda list
       - name: Run tests
-        shell: bash -l {0}
         run: |
-          conda activate climpred-minimum-tests
-          pytest --cov=climpred --cov-report=xml
+          pytest --cov=climpred --cov-report=xml --verbose
       - name: Upload coverage to codecov
         uses: codecov/codecov-action@v1.0.7
         with:
@@ -41,28 +45,32 @@ jobs:
 
   docs_notebooks:  # Checks that pre-compiled notebooks in docs still work.
     runs-on: ubuntu-latest
+    defaults:
+        run:
+          shell: bash -l {0}
     steps:
       - uses: actions/checkout@v2
         with:
           ref: ${{github.event.pull_request.head.ref}}
           repository: ${{github.event.pull_request.head.repo.full_name}}
-      - name: Install Conda environment
+      - name: Set up Conda
         uses: conda-incubator/setup-miniconda@v1
         with:
           auto-update-conda: true
+          channels: conda-forge
+          mamba-version: '*'
           activate-environment: climpred-docs-notebooks
-          environment-file: ci/requirements/docs_notebooks.yml
           python-version: 3.6
+      - name: Set up conda environment
+        run: |
+          mamba env update -f ci/requirements/docs_notebooks.yml
       - name: Conda info
-        shell: bash -l {0}
         run: conda info
       - name: Conda list
-        shell: bash -l {0}
         run: conda list
       - name: Test notebooks in docs
-        shell: bash -l {0}
         run: |
           pushd docs
           nbstripout source/*.ipynb source/examples/decadal/*.ipynb source/examples/subseasonal/*.ipynb
-          make html
+          make -j4 html
           popd

ci/requirements/minimum-tests.yml

@@ -1,18 +1,25 @@
 name: climpred-minimum-tests
 channels:
   - conda-forge
-  - defaults
 dependencies:
-  - xesmf
-  - esmpy
+  - cftime>=1.1.2
+  - coveralls
   - dask
-  - netcdf4
+  - eofs
+  - esmpy=*=mpi*
+  - esmtools>=1.1.3
   - ipython
+  - matplotlib
   - nc-time-axis
-  - coveralls
+  - netcdf4
+  - pip
   - pytest
   - pytest-cov
-  - pip
+  - scipy
+  - xarray>=0.16.1
+  - xesmf
+  - xrft
+  - xskillscore>=0.0.18
   - pip:
     - pytest-lazy-fixture
     - -e ../..