ci: Test the petl executable

 - adds a simple test invoking the petl executable
 - installs the package in CI so the executable is available.

.github/workflows/test-changes.yml

@@ -91,6 +91,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           python -m pip install --prefer-binary -r requirements-tests.txt
+          python -m pip install -e .
 
       - name: Setup environment variables for remote filesystem testing
         if: matrix.os == 'ubuntu-latest' && matrix.python == '3.8'

petl/test/test_executable.py

@@ -0,0 +1,10 @@
+from __future__ import print_function, division, absolute_import
+
+import subprocess
+
+def test_executable():
+    result = subprocess.run("""
+        (echo foo,bar ; echo a,b; echo c,d) |
+        petl 'fromcsv().cut("foo").head(1).tocsv()'
+    """, shell=True, check=True, capture_output=True)
+    assert result.stdout == b'foo\r\na\r\n'