diff --git a/clean_files.txt b/clean_files.txt
index 242d7327..ad9a364a 100644
--- a/clean_files.txt
+++ b/clean_files.txt
@@ -122,6 +122,7 @@ plugins/available/zoxide.plugin.bash
 # tests
 #
 test/plugins/alias-completion.plugin.bats
+test/run
 test/test_helper.bash
 test/test_helper_libs.bash
 
diff --git a/test/run b/test/run
index 7999d4fb..14d83950 100755
--- a/test/run
+++ b/test/run
@@ -4,16 +4,15 @@ bats_executable="${test_directory}/../test_lib/bats-core/bin/bats"
 
 git submodule init && git submodule update
 
-if [ -z "${BASH_IT}" ]; then
-  declare BASH_IT
-  BASH_IT="$(cd "${test_directory}" && dirname "${PWD}")"
-  export BASH_IT
+if [[ -z "${BASH_IT}" ]]; then
+	BASH_IT="$(cd "${test_directory}" && dirname "${PWD}")"
+	export BASH_IT
 fi
 
-if [ -z "$1" ]; then
-  test_dirs=( "${test_directory}"/{bash_it,completion,install,lib,plugins,themes} )
+if [[ -z "$1" ]]; then
+	test_dirs=("${test_directory}"/{bash_it,completion,install,lib,plugins,themes})
 else
-  test_dirs=( "$1" )
+	test_dirs=("$1")
 fi
 
 # Make sure that the `parallel` command is installed,
@@ -21,28 +20,26 @@ fi
 # If that is the case, try to guess the number of CPU cores,
 # so we can run `bats` in parallel processing mode, which is a lot faster.
 if command -v parallel &> /dev/null \
-  && parallel -V &> /dev/null \
-  && { parallel -V 2> /dev/null | grep -q '^GNU\>'; }
-then
-  # Expect to run at least on a dual-core CPU; slightly degraded performance
-  # shouldn't matter otherwise.
-  declare -i -r test_jobs_default=2
-  declare -i -r test_jobs_effective="$(
-    if [ "${TEST_JOBS:-detect}" = "detect" ] \
-      && command -v nproc &> /dev/null
-    then
-      nproc
-    elif [ -n "${TEST_JOBS}" ] \
-      && [ "${TEST_JOBS}" != "detect" ]
-    then
-      echo "${TEST_JOBS}"
-    else
-      echo ${test_jobs_default}
-    fi
-  )"
-  exec "$bats_executable" ${CI:+--tap} --jobs ${test_jobs_effective} \
-    "${test_dirs[@]}"
+	&& parallel -V &> /dev/null \
+	&& { parallel -V 2> /dev/null | grep -q '^GNU\>'; }; then
+	# Expect to run at least on a dual-core CPU; slightly degraded performance
+	# shouldn't matter otherwise.
+	declare -i -r test_jobs_default=2
+	# shellcheck disable=SC2155
+	declare -i -r test_jobs_effective="$(
+		if [[ "${TEST_JOBS:-detect}" = "detect" ]] \
+			&& command -v nproc &> /dev/null; then
+			nproc
+		elif [[ -n "${TEST_JOBS}" ]] \
+			&& [[ "${TEST_JOBS}" != "detect" ]]; then
+			echo "${TEST_JOBS}"
+		else
+			echo "${test_jobs_default}"
+		fi
+	)"
+	exec "$bats_executable" "${CI:+--tap}" --jobs "${test_jobs_effective}" \
+		"${test_dirs[@]}"
 else
-  # Run `bats` in single-threaded mode.
-  exec "$bats_executable" ${CI:+--tap} "${test_dirs[@]}"
+	# Run `bats` in single-threaded mode.
+	exec "$bats_executable" ${CI:+--tap} "${test_dirs[@]}"
 fi