[GiotHub Actions] explicitly use virtual env

.github/workflows/testing_external_plugins.yaml

@@ -30,8 +30,6 @@ jobs:
         exclude: # Added for GitHub Actions PR problem 2020-12-19 -- remove later!
           - os: windows-latest
             python-version: 3.9
-          - os: windows-latest
-            python-version: 3.8
 
     steps:
     - uses: actions/checkout@v2
@@ -47,40 +45,37 @@ jobs:
         path: .venv
         key: ${{ runner.os }}-${{ hashFiles('poetry.lock') }}-${{ matrix.python-version }}-v2-namespace-plugins
 
-    - name: Set up and Activate Virtual Environment (Linux)
-      if: startsWith(matrix.os, 'ubuntu')
-      run: |
-        python -m venv .venv
-        source .venv/bin/activate
-
-    - name: Set up and Activate Virtual Environment (Mac)
-      if: startsWith(matrix.os, 'macOS')
-      run: |
-        python -m venv .venv
-        source .venv/bin/activate
-
-    - name:  Set up and Activate Virtual Environment (Windows)
-      if: startsWith(matrix.os, 'windows')
-      run: |
-        python -m venv .venv
-        venv/Scripts/activate
-
-    - name: Install dependencies
+    - name: Install dependencies (1 of 2)
       run: |
         python -m pip install pip --upgrade
         pip install poetry
         poetry config --local virtualenvs.in-project true
         poetry install --remove-untracked
         poetry install
-        poetry run python -m pip install ./tests/external_plugins_src/
+
+    - name: Activate Virtual Environment (Linux)
+      if: startsWith(matrix.os, 'ubuntu')
+      run: source .venv/bin/activate
+
+    - name: Activate Virtual Environment (Mac)
+      if: startsWith(matrix.os, 'macOS')
+      run: source .venv/bin/activate
+
+    - name:  Activate Virtual Environment (Windows)
+      if: startsWith(matrix.os, 'windows')
+      run: venv/Scripts/activate
+
+    - name: Install dependencies (2 of 2)
+      run: |
+        python -m pip install ./tests/external_plugins_src/
         cd features
     # installed test plugins aren't recognized by "behave" if run from the
     # project's root folder
 
     - name: Test with pytest
       if: success() || failure()
-      run: poetry run pytest --junitxml=../reports/pytest/results.xml
+      run: pytest --junitxml=../reports/pytest/results.xml
 
     - name: Test with behave
       if: success() || failure()
-      run: poetry run behave --no-skipped --format progress2 --junit --junit-directory ../reports/behave
+      run: behave --no-skipped --format progress2 --junit --junit-directory ../reports/behave