Introduce assert_failure

bin/git-check-assertions

@@ -46,7 +46,13 @@ assert_success() {
     exit 1
   fi
 }
-export -f run assert_success
+assert_failure() {
+  if [ "$status" -eq 0 ]; then
+    echo "Expected command to fail, but it succeeded."
+    exit 1
+  fi
+}
+export -f run assert_success assert_failure
 
 # main flow
 orig_ref="$(git symbolic-ref --quiet --short HEAD || git rev-parse HEAD)"

test/git-check-assertions.bats

@@ -131,3 +131,22 @@ commit_with_assertion() {
   assert_failure
   assert_output --partial "Expected command to succeed, but it failed."
 }
+
+@test "assert_failure should succeed if the executed command failed" {
+  git checkout -b feature
+  commit_with_assertion $'run exit 1\nassert_failure'
+
+  run git-check-assertions
+
+  assert_success
+}
+
+@test "assert_failure should fail if the executed command succeeded" {
+  git checkout -b feature
+  commit_with_assertion $'run exit 0\nassert_failure'
+
+  run git-check-assertions
+
+  assert_failure
+  assert_output --partial "Expected command to fail, but it succeeded."
+}