Raise the cyclomatic complexity to 10 which seems to better match the project coding style and still reasonable (6 being quite low). Also move unit tests specific eslint rules in the cascaded `./test/.eslintrc` file (previously in `gulp.js`).
Coverage data are now generated by running `gulp unittest` with the `--coverage` argument: unit tests are then executed a single time on Travis. The gulp `coverage` task has been removed and `karma.coverage.conf.ci.js` merged into `karma.conf.ci.js`.
Update documentation with gulp commands (and remove them from `README.md`) and remove unused `config.jshintrc` (oversight from #3256). Delete `thankyou.md` which has been merged into `README.md`.
Attempt to make easier the creation of unit tests that check the drawing output. Until now, this was done by checking calls on a 'fake' context, which is hard to maintain (need to update pixel values by hands) and also not reliable when optimizing code (i.e. different calls sequence but same result).
As of now, it's possible to define 'auto' tests based on JSON/PNG fixtures: chart is generated from the JSON file and compared to the associated PNG image. The image diff is done using `pixelmatch`. As an example (and in preparation of the `filler` plugin), add auto tests for the line element `fill` options.
`karma.conf.ci.js` has been merged into `karma.conf.js` for local testing consistency: `gulp unittestWatch` has been replaced by `gulp unittest --watch` and thus use exactly the same config file. Upgrade to latest jasmine and karma packages and remove deprecated `gulp-karma` dependency (directly use `karma.Server` in gulp).
Split `test/mockContext.js` into smaller `test/jasmine.*` modules to make easier unit tests maintenance and finally, move all `*.test.js` files under the `test/specs` folder.
Add the --inputs command switch to the unittest and unittestWatch tasks, to be able to run unit tests from the specified files only (e.g. gulp unittest --inputs=test/core.element.tests.js;test/core.helpers.tests.js).
Change the linter in gulp tasks to be consistent with Code Climate results which are based on ESLint using .eslintrc options. However, defaults Code Climate rules are too strict, so turn as warnings the 'complexity' and 'max-statements' rules (other errors has been fixed). Note that the Gulp task name has been changed for `gulp lint`.
Samples need to be packaged with built libraries (which one have been removed from the repository), so create a new `gulp package` task to generate a ZIP archive with dist files, samples and the license file. This archive is generated in the ./dist/ folder and will be deployed by Travis along the GH release. Note that the ./dist/ folder is not preserved but merged in the archive root. Also change samples requiring moment.js to load this lib from the CDN instead of the ./node_module folder.
