split up unit-tests and use 4 containers (they're free)

tests/ci/unit_test_runner.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+
+is_number() {
+  local NUMBER=$1; local NUM_RE='^[0-9]+$'
+  if [[ $NUMBER =~ $NUM_RE ]];then
+    return 0
+  else
+    return 1
+  fi
+}
+
+usage() {
+  echo "usage: $0 1|2"
+  exit 0
+}
+
+BATCH_NUM="$1"
+is_number $BATCH_NUM || usage
+
+TESTS=( $(find $(dirname $0)/../unit -maxdepth 1 -name "*.bats") )
+HALF_TESTS=$(( ${#TESTS[@]} / 2 ))
+FIRST_HALF=${TESTS[@]:0:${HALF_TESTS}}
+LAST_HALF=${TESTS[@]:${HALF_TESTS}:${#TESTS[@]}}
+
+case "$BATCH_NUM" in
+  1)
+    bats $FIRST_HALF
+  ;;
+
+  2)
+    bats $LAST_HALF
+  ;;
+
+  *)
+    usage
+  ;;
+esac