workflows/selftest: regression test for no output

Signed-off-by: Andrew Pan <a@tny.town>

.github/workflows/selftest.yml

@@ -88,3 +88,21 @@ jobs:
           PIP_AUDIT_OUTPUT: "${{ steps.pip-audit.outputs.internal-be-careful-output }}"
         run: |
           grep -E 'pyyaml\s+\|\s+5.1' <<< $(base64 -d <<< "${PIP_AUDIT_OUTPUT}")
+  selftest-pipaudit-fail:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ./
+        id: pip-audit
+        with:
+          # we do not care about pip-audit's actual output in this test, we just need a file to pass
+          # in so as to not exercise `pip list` mode.
+          inputs: ./test/empty.txt
+          # pass in a fake flag here to reliably trigger the failure we're looking for.
+          internal-be-careful-extra-flags: --not-a-real-pip-audit-flag
+          internal-be-careful-allow-failure: true
+      - name: assert expected output
+        env:
+          PIP_AUDIT_OUTPUT: "${{ steps.pip-audit.outputs.internal-be-careful-output }}"
+        run: |
+          grep 'pip-audit did not return any output' <<< $(base64 -d <<< "${PIP_AUDIT_OUTPUT}")

action.py

@@ -135,18 +135,20 @@ def _fatal_help(msg):
 else:
     _summary("❌ pip-audit found one or more problems")
 
+    output = "⚠️ pip-audit did not return any output"
     try:
-        with open("/tmp/pip-audit-output.txt") as io:
+        with open("/tmp/pip-audit-output.txt", "r") as io:
             output = io.read()
-
-            # This is really nasty: our output contains multiple lines,
-            # so we can't naively stuff it into an output.
-            print(f"output={b64encode(output.encode()).decode()}", file=_GITHUB_OUTPUT)
-
-            _log(output)
-            _summary(output)
     except OSError as ex:
         _log(ex)
+        _summary("❌ pip-audit did not return any output")
+
+    # This is really nasty: our output contains multiple lines,
+    # so we can't naively stuff it into an output.
+    print(f"output={b64encode(output.encode()).decode()}", file=_GITHUB_OUTPUT)
+
+    _log(output)
+    _summary(output)
 
 
 _log(status.stdout)