Add rudimentary grep for runtime warnings in CI

.github/workflows/ci-workflow.yml

@@ -49,4 +49,5 @@ jobs:
       - run: mix deps.compile
       - run: mix compile --warnings-as-errors
       - run: mix test
+      - run: ./test/runtime_warnings.sh
       - run: ./test/smoke_test.sh

test/error_if_warnings.sh

@@ -0,0 +1,8 @@
+grep -E "^warning: .+" --after-context=6 <&0
+
+if [ $? -eq 0 ]
+then
+  exit 1
+else
+  exit 0
+fi

test/runtime_warnings.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+set -e
+
+mix compile --force --warnings-as-errors
+
+
+mix credo --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo --strict --enable-disabled-checks . --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo --strict --enable-disabled-checks . --mute-exit-status --format=json | ./test/error_if_warnings.sh
+
+mix credo lib/credo.ex --read-from-stdin --strict < lib/credo.ex | ./test/error_if_warnings.sh
+
+mix credo list --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo suggest --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo diff HEAD^ --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo diff v1.4.0 --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo explain test/fixtures/example_code/clean_redux.ex:1:11 --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo explain Credo.Check.Refactor.Nesting --mute-exit-status | ./test/error_if_warnings.sh
+
+mix credo categories | ./test/error_if_warnings.sh
+
+mix credo info --verbose | ./test/error_if_warnings.sh
+
+mix credo version | ./test/error_if_warnings.sh
+
+mix credo help | ./test/error_if_warnings.sh
+
+
+echo ""
+echo "Smoke test for runtime warnings successful."