Splits tests across multiple Circle CI nodes manually.

circleci-parallel.sh

#!/bin/bash

# Add this script to your code in the root directory, then add the following to your circle.yml
# test:
#   override:
#     - ./circleci-parallel.sh:
#         parallel: true

while getopts ":hp:" opt; do
  case $opt in
    h)
      echo ""
      echo "circleci-parallel.sh"
      echo "-----------"
      echo "Runs tests in parallel on Circle CI, or locally… like whatever."
      echo ""
      echo "Options:"
      echo ""
      echo "         -h Prints this help message (duh)."
      echo ""
      echo "  -p [path] Temporarily add a directory to the end of PATH. Useful"
      echo "            if the script can't find the local binaries."
      echo ""
      echo "Example:"
      echo ""
      echo "            ./circleci-parallel.sh -p ~/src/my-code/vendor-modules/bin"
      echo ""
      echo "That is all."
      echo ""
      exit 0;
      ;;
    p)
      if [ -d "$OPTARG" ];
      then
        PATH="$PATH:$OPTARG";
      else
        echo "Invalid path supplied to -p option." >&2;
        exit 1;
      fi
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2;
      exit 2;
      ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2;
      exit 3;
      ;;
  esac
done

function echo_b() {
  echo "";
  echo ">>> ===============================================";
  echo ">>> $1";
  echo ">>> ===============================================";
}

function reset_db() {
  echo_b "Reseting database...";
  # Do stuff to reset the database
}

function reseed_db() {
  echo_b "Re-seeding database...";
  # Do stuff to re-seed the database
}

function run_server() {
  echo_b "Preparing environment...";
  reset_db &&
  reseed_db;

  echo_b "Building distribution...";
  # Build the server if there is a build step

  echo_b "Running server...";
  # Start the server

  # Add a delay if the server needs some extra time to start or settle
  for (( i = 10; i > 0; i-- )); do
    printf "%i… " $i;
    sleep 1;
  done
  printf "Let's Go!";
  sleep 1;
  return 0;
}

function run_linter() {
  echo_b "Running linter...";
  # Run the linter
}

function run_test_suite_one() {
  echo_b "Running test suite one...";
  # Run test suite one
}

function run_test_suite_two() {
  echo_b "Running test suite two...";
  # Run test suite two
}

function run_test_suite_three() {
  echo_b "Running test suite three...";
  # Run test suite three
}

function run_test_suite_four() {
  echo_b "Running test suite four...";
  # Run test suite four
}

# Execute based on number of Circle CI nodes, and which Circle CI node is running
case $CIRCLE_NODE_TOTAL in
  "" | 1 )
    # This case is triggered when there is only one Circle CI node, or when run locally
    echo_b "Will run all tests";
    run_linter &&
    run_server &&
    run_test_suite_one &&
    run_test_suite_two &&
    run_test_suite_three &&
    run_test_suite_four;
    ;;
  2 )
    # This case is triggered when there are two Circle CI nodes
    case $CIRCLE_NODE_INDEX in
      0 )
        # These commands will run on the first Circle CI node
        echo_b "Will run linter, test suite one, and test suite two";
        run_linter &&
        run_server &&
        run_test_suite_one &&
        run_test_suite_two;
        ;;
      1 )
        # These commands will run on the second Circle CI node
        echo_b "Will run test suite three and test suite four";
        run_server &&
        run_test_suite_three &&
        run_test_suite_four;
        ;;
    esac
    ;;
  3 )
    # This case is triggered when there are three Circle CI nodes
    case $CIRCLE_NODE_INDEX in
      0 )
        # These commands will run on the first Circle CI node
        echo_b "Will run linter, test suite one, and test suite two";
        run_linter &&
        run_server &&
        run_test_suite_one &&
        run_test_suite_two;
        ;;
      1 )
        # These commands will run on the second Circle CI node
        echo_b "Will run test suite three";
        run_server &&
        run_test_suite_three;
        ;;
      2 )
        # These commands will run on the third Circle CI node
        echo_b "Will run test suite four";
        run_server &&
        run_test_suite_four;
        ;;
    esac
    ;;
  * )
    # This case is triggered when there are four or more Circle CI nodes
    case $CIRCLE_NODE_INDEX in
      0 )
        # These commands will run on the first Circle CI node
        echo_b "Will run linter and test suite one";
        run_linter &&
        run_server &&
        run_test_suite_one;
        ;;
      1 )
        # These commands will run on the second Circle CI node
        echo_b "Will run test suite two";
        run_server &&
        run_test_suite_two;
        ;;
      2 )
        # These commands will run on the third Circle CI node
        echo_b "Will run test suite three";
        run_server &&
        run_test_suite_three;
        ;;
      3 )
        # These commands will run on the fourth Circle CI node
        echo_b "Will run test suite four";
        run_server &&
        run_test_suite_four;
        ;;
      * )
        # This warning will display on the fifth or any later Circle CI node
        echo_b "We only split tests across a maximum of 4 nodes";
        exit 0;
    esac
    ;;
esac