Add mypy validation action

Author: anselor

.github/workflows/mypy.yml

@@ -0,0 +1,28 @@
+# For documentation on GitHub Actions Workflows, see:
+# https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions
+name: MyPy
+
+on: [push, pull_request]
+
+jobs:
+  mypy:
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+        python-version: [3.9]
+      fail-fast: false
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2  # https://github.com/actions/checkout
+        with:
+          # Only a single commit is fetched by default, for the ref/SHA that triggered the workflow.
+          # Set fetch-depth: 0 to fetch all history for all branches and tags.
+          fetch-depth: 0 # Needed for setuptools_scm to work correctly
+      - name: Set up Python
+        uses: actions/setup-python@v2  # https://github.com/actions/setup-python
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install python prerequisites
+        run: pip install -U --user pip setuptools setuptools-scm mypy
+      - name: MyPy
+        run: python -m mypy cmd2

cmd2/cmd2.py

@@ -399,7 +399,7 @@ def __init__(
             if os.path.exists(startup_script):
                 script_cmd = "run_script {}".format(utils.quote_string(startup_script))
                 if silent_startup_script:
-                    script_cmd += "> {}".format(os.devnull)
+                    script_cmd += " > {}".format(os.devnull)
                 self._startup_commands.append(script_cmd)
 
         # Transcript files to run instead of interactive command loop

cmd2/table_creator.py

@@ -138,7 +138,7 @@ def __init__(self, cols: Sequence[Column], *, tab_width: int = 4) -> None:
 
             # For headers with the width not yet set, use the width of the
             # widest line in the header or 1 if the header has no width
-            if col.width < 0:
+            if col.width <= 0:
                 col.width = max(1, ansi.widest_line(col.header))
 
     @staticmethod