Extract common create_hook helper

test/rbenv.bats

@@ -70,6 +70,7 @@ load test_helper
 }
 
 @test "RBENV_HOOK_PATH includes rbenv built-in plugins" {
+  unset RBENV_HOOK_PATH
   run rbenv echo "RBENV_HOOK_PATH"
   assert_success "${RBENV_ROOT}/rbenv.d:${BATS_TEST_DIRNAME%/*}/rbenv.d:/usr/local/etc/rbenv.d:/etc/rbenv.d:/usr/lib/rbenv/hooks"
 }

test/test_helper.bash

@@ -17,6 +17,7 @@ if [ -z "$RBENV_TEST_DIR" ]; then
 
   export RBENV_ROOT="${RBENV_TEST_DIR}/root"
   export HOME="${RBENV_TEST_DIR}/home"
+  export RBENV_HOOK_PATH="${RBENV_ROOT}/rbenv.d"
 
   PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin
   PATH="${RBENV_TEST_DIR}/bin:$PATH"
@@ -129,3 +130,11 @@ path_without() {
   path="${path#:}"
   echo "${path%:}"
 }
+
+create_hook() {
+  mkdir -p "${RBENV_HOOK_PATH}/$1"
+  touch "${RBENV_HOOK_PATH}/$1/$2"
+  if [ ! -t 0 ]; then
+    cat > "${RBENV_HOOK_PATH}/$1/$2"
+  fi
+}