Outsourced linting tests into its own file (#1636)

* outsourced linting tests into its own file
* trigger rebuild
* added SCRIPT variable to setup.sh
* trigger rebuild again
* major test rewrite
* outsourced `hadolint` too
* rewrote some parts of the linting logic due to a logic bug
* adjusted TravisCI
* corrected .bats test line
* corrected logging in linting tests
* updated `hadolint`

setup.sh

@@ -3,12 +3,24 @@
 # Wrapper for various setup scripts
 # included in the docker-mailserver
 
-set -euEo pipefail
-trap '_report_err ${_} ${LINENO} ${?}' ERR
+SCRIPT='SETUP'
 
-function _report_err
+set -euEo pipefail
+trap '__log_err ${FUNCNAME[0]:-"?"} ${_:-"?"} ${LINENO:-"?"} ${?:-"?"}' ERR
+
+function __log_err
 {
-  echo "ERROR occured :: source ${1} ; line ${2} ; exit code ${3} ;;" >&2
+  local FUNC_NAME LINE EXIT_CODE
+  FUNC_NAME="${1} / ${2}"
+  LINE="${3}"
+  EXIT_CODE="${4}"
+
+  printf "\n––– \e[1m\e[31mUNCHECKED ERROR\e[0m\n%s\n%s\n%s\n%s\n\n" \
+    "  – script    = ${SCRIPT,,}.sh" \
+    "  – function  = ${FUNC_NAME}" \
+    "  – line      = ${LINE}" \
+    "  – exit code = ${EXIT_CODE}"
+
   _unset_vars
 }
 
@@ -88,7 +100,9 @@ function _inspect
 
 function _usage
 {
-  echo "Usage: ${0} [-i IMAGE_NAME] [-c CONTAINER_NAME] <subcommand> <subcommand> [args]
+  echo "${SCRIPT,,}.sh
+
+Usage: ${0} [-i IMAGE_NAME] [-c CONTAINER_NAME] <subcommand> <subcommand> [args]
 
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