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Using createDartAnalyzerTask in bot.dart to Ensure Sanity

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drone.io has really proven to be useful for dart projects. One common pattern I find my self doing with projects these days is running the dart_analyzer before running unit tests. Had a discussion with Kevin Moore about having a dart_analyzer task included in hop, part of the bot.dart framework. We both agreed it would be nice to automate that task and not have shell scripts running the show. Thus createDartAnalyzerTask was born. createDartAnalyzerTask allows you to add dart scripts that are libraries or main entry points to be analyzed by dart_analyzer, this allows for a first step of safety, so that code you have passes the static checker. It does not mean your code is perfect but can help you find warnings and errors. A great combination for this is pairing it up with drone.io, that way when a new sdk comes out drone can let you know automatically if it passes static checker.

Lets see this in action

First step is to add bot to your pubspec.yaml

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dependencies:
  browser: ">=0.3.4"
  unittest: ">=0.3.4"
  bot: ">=0.12.0"

Create a minimal tool/hop_runner.dart

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library hop_runner;

import 'dart:async';
import 'dart:io';
import 'package:bot/bot.dart';
import 'package:bot/hop.dart';
import 'package:bot/hop_tasks.dart';

void main() {
  //
  // Analyzer
  //
  addTask('analyze_lib', createDartAnalyzerTask(['lib/stats.dart']));

  //
  // Hop away!
  //
  runHopCore();
}

Add a bin/hop script to your project, bin/hop script is not required but does help manage some flags you might be interested in having.

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#!/bin/bash
PACK_DIR=`pwd`/packages/
cmd="dart
--enable_asserts
--enable_checked_mode
--enable_type_checks
--error_on_malformed_type
--package-root=$PACK_DIR
--verbose_debug
--warning_as_error
./tool/hop_runner.dart $@"
exec $cmd

Now hop away!

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19:41:54-adam@Adams-MacBook-Air:~/dart/stats.dart
$ hop analyze_lib
analyze_lib: PASSED - lib/stats.dart
analyze_lib: PASSED: 1, WARNING: 0, ERROR: 0
Finished

Now lets say we have the following warning of String i = 42;, bot can provide us a summary of warnings we might have in our code.

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library not_cool_lib;

void main() {
  String i = 42;
}

Adding the library to our task

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  //
  // Analyzer
  //
  addTask('analyze_lib', createDartAnalyzerTask(['lib/stats.dart', 'lib/notcoollib.dart']));

Executing hop

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20:04:55-adam@Adams-MacBook-Air:~/dart/stats.dart
$ hop analyze_lib
analyze_lib: PASSED - lib/stats.dart
analyze_lib: WARNING - lib/notcoollib.dart
analyze_lib: PASSED: 1, WARNING: 1, ERROR: 0
Finished

Now we have a warning, but since dart is a dynamic langauge we should not treat that as an error (at some point we might provide the option of making warnings fail drone.io).

If we introduce a real error, the task runner should yell at us.

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library not_cool_lib;

void main() {
  String i = 42;
  bam(i);
}

And it does!

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20:11:38-adam@Adams-MacBook-Air:~/dart/stats.dart
$ hop analyze_lib
analyze_lib: PASSED - lib/stats.dart
analyze_lib: ERROR - lib/notcoollib.dart
analyze_lib: PASSED: 1, WARNING: 0, ERROR: 1
analyze_lib: Failed
Failed
20:18:11-adam@Adams-MacBook-Air:~/dart/stats.dart
$ echo $?
80

The exit code will let drone.io know that we did not exit cleanly. I love drone.io for this reason, it’s simple to get setup right away with little fuss.

A complete run on drone.io might look something as follows

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$ git clone git://github.com/Dartist/stats.dart.git /home/ubuntu/src/github.com/Dartist/stats.dart 
Cloning into '/home/ubuntu/src/github.com/Dartist/stats.dart'...
$ dart --version
Dart VM version: 0.3.4.0_r18115 (Tue Feb  5 05:53:42 2013)
$ cat $DART_SDK/revision
18137
$ sudo start xvfb
xvfb start/running, process 1017
$ pub install
Resolving dependencies...
Downloading browser 0.3.4...
Downloading bot 0.12.1...
Downloading unittest 0.3.4...
Downloading logging 0.3.4...
Downloading args 0.3.4...
Downloading meta 0.3.4...
Dependencies installed!
$ export PATH=./bin:$PATH
$ hop analyze_lib
analyze_lib: PASSED - lib/stats.dart
analyze_lib: PASSED: 1, WARNING: 0, ERROR: 0
Finished
$ hop headless_test
unittest-suite-wait-for-done
headless_test: DumpRenderTree - test/tests_browser.html
headless_test: 1 PASSED, 0 FAILED, 0 ERRORS
Finished

For a full example of a project that uses bot.dart for testing and analyzer please refer to stats.dart

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