[tests] make setup function to create test dir per test

test/plugins/base.plugin.bats

@@ -27,7 +27,6 @@ load ../../plugins/available/base.plugin
 }
 
 @test 'plugins base: pickfrom()' {
-  mkdir -p $BASH_IT_ROOT
   stub_file="${BASH_IT_ROOT}/stub_file"
   printf "l1\nl2\nl3" > $stub_file
   run pickfrom $stub_file
@@ -50,7 +49,6 @@ load ../../plugins/available/base.plugin
 }
 
 @test 'plugins base: buf()' {
-  mkdir -p $BASH_IT_ROOT
   declare -r file="${BASH_IT_ROOT}/file"
   touch $file
   run buf $file

test/test_helper.bash

@@ -13,8 +13,12 @@ if [ "$BASH_IT_ROOT" != "${BASH_IT_TEST_DIR}/root" ]; then
   export BASH_IT=$BASH_IT_TEST_DIR
 fi
 
+setup() {
+  mkdir -p -- "${BASH_IT_ROOT}"
+}
+
 teardown() {
-  rm -rf "$BASH_IT_TEST_DIR"
+  rm -rf "${BASH_IT_TEST_DIR}"
 }
 
 assert() {