CI for pre-release (#7220)

* ci for pre-release

* .

* drop 3.7

.github/workflows/ci_test-full.yml

@@ -18,11 +18,17 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-18.04, windows-2019, macOS-10.15]
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: [3.6, 3.8, 3.9]
         requires: ['minimal', 'latest']
+        release: ['stable']
         exclude:
           - python-version: 3.9
             requires: 'minimal'
+        include:
+          - os: ubuntu-20.04
+            python-version: 3.9
+            requires: 'latest'
+            release: 'pre'
 
     # Timeout: https://stackoverflow.com/a/59076067/4521646
     # TODO: the macOS is taking too long, probably caching did not work...
@@ -96,9 +102,9 @@ jobs:
       uses: actions/cache@v2
       with:
         path: ${{ steps.pip-cache.outputs.dir }}
-        key: ${{ runner.os }}-pip-py${{ matrix.python-version }}-${{ matrix.requires }}-${{ hashFiles('requirements.txt') }}-${{ hashFiles('requirements/extra.txt') }}
+        key: ${{ runner.os }}-pip-py${{ matrix.python-version }}-${{ matrix.release }}-${{ matrix.requires }}-${{ hashFiles('requirements.txt') }}-${{ hashFiles('requirements/extra.txt') }}
         restore-keys: |
-          ${{ runner.os }}-pip-py${{ matrix.python-version }}-${{ matrix.requires }}-
+          ${{ runner.os }}-pip-py${{ matrix.python-version }}-${{ matrix.release }}-${{ matrix.requires }}-
 
     - name: Pull checkpoints from S3
       run: |
@@ -126,7 +132,8 @@ jobs:
         python --version
         pip --version
         # python -m pip install --upgrade --user pip
-        pip install --requirement requirements.txt --find-links https://download.pytorch.org/whl/cpu/torch_stable.html --upgrade
+        flag=$(python -c "print('--pre' if '${{matrix.release}}' == 'pre' else '')" 2>&1)
+        pip install --requirement requirements.txt --find-links https://download.pytorch.org/whl/cpu/torch_stable.html --upgrade $flag
         # adjust versions according installed Torch version
         python ./requirements/adjust_versions.py requirements/extra.txt
         python ./requirements/adjust_versions.py requirements/examples.txt
@@ -158,7 +165,7 @@ jobs:
     - name: Tests
       run: |
         # NOTE: do not include coverage report here, see: https://github.com/nedbat/coveragepy/issues/1003
-        coverage run --source pytorch_lightning -m pytest pytorch_lightning tests -v --durations=50 --junitxml=junit/test-results-${{ runner.os }}-py${{ matrix.python-version }}-${{ matrix.requires }}.xml
+        coverage run --source pytorch_lightning -m pytest pytorch_lightning tests -v --durations=50 --junitxml=junit/test-results-${{ runner.os }}-py${{ matrix.python-version }}-${{ matrix.requires }}-${{ matrix.release }}.xml
 
     - name: Examples
       run: |
@@ -167,8 +174,8 @@ jobs:
     - name: Upload pytest results
       uses: actions/upload-artifact@v2
       with:
-        name: pytest-results-${{ runner.os }}-${{ matrix.python-version }}-${{ matrix.requires }}
-        path: junit/test-results-${{ runner.os }}-${{ matrix.python-version }}-${{ matrix.requires }}.xml
+        name: pytest-results-${{ runner.os }}-${{ matrix.python-version }}-${{ matrix.requires }}-${{ matrix.release }}
+        path: junit/test-results-${{ runner.os }}-${{ matrix.python-version }}-${{ matrix.requires }}-${{ matrix.release }}.xml
       if: failure()
 
     - name: Statistics