next-update/docs/use.md

Also check out: 

* [next-updater](https://github.com/bahmutov/next-updater) can update all your repos
* [dont-break](https://github.com/bahmutov/dont-break) 
that checks if your code is going to break everyone who depends on it.
* [changed-log](https://github.com/bahmutov/changed-log) returns commit messages for
the given NPM package or Github repo between two tags.

## Example

Imagine your nodejs module *foo* has the following dependencies listed in *package.json*

    "dependencies": {
        "lodash": "~1.2.0",
        "async": "~0.2.5"
    }

You would like to update lodash and async to latest versions, to not sure if
this would break anything. With *next-update* it is easy: run command `next-update`
in the folder with module *foo*. Here is the example output:

    next updates:
    lodash
        1.2.1 PASS
    async
        0.2.6 PASS
        0.2.7 PASS
        0.2.8 PASS


Both *package.json* file and *node_modules* folder are left unchanged,
and now you know that you can safely upgrade both libraries to later versions.

### It even tells you the install command ;)

    Use the following command to install working versions
    npm install --save lodash@2.1.0

This might not appear like a big deal for a single module that is using
popular 3rd party libraries with stable apis only. *next-update* is most useful
in the larger development context, where multiple modules are being developed
side by side, often by different teams. In such situations, checking if an upgrade
is possible could be part of the continuous build pipeline.

You can see if your dependencies are out of date by using
[david](https://david-dm.org),
it even has badges you can add to your README files.

*next-update* reports the probability of success for a given dependency update using
anonymous global statistics from [next-update](http://next-update.herokuapp.com/) server

```
available updates:
package               available  from version  average success %  successful updates  failed updates
--------------------  ---------  ------------  -----------------  ------------------  --------------
grunt-contrib-jshint  0.8.0      0.7.2         100%               34                  0
grunt-bump            0.0.13     0.0.12        100%               4                   0
```

## Install

    npm install -g next-update  // installs module globally
    next-update --help          // shows command line options

## Anonymous usage collection

After testing each module A upgrade from version X to Y, *next-update* sends
anonymous result to [http://next-update.herokuapp.com/](http://next-update.herokuapp.com/).
The only information transmitted is:

```json
{
    "name": "lodash",
    "from": "1.0.0",
    "to": "2.0.0",
    "success": true
}
```

This information is used to answer the following questions later:
what is the probability module A can be upgraded from X to Y?
Thus even if you do not have tests covering this particular module,
you can judge how compatible version X and Y really are over the entire
internet.

You can inspect data send in
[stats.js](https://github.com/bahmutov/next-update/blob/master/src/stats.js).

If the dependency module has been upgraded by anyone else, its statistics
will be displayed with each test.

```sh
stats: deps-ok 0.0.7 -> 0.0.8 success probability 44.44% 8 success(es) 10 failure(s)
```

A lot of NPM modules [do not have tests](http://npmt.abru.pt/), but
at least you can judge if someone else has success going from verion X to version Y
of a dependency.

## Use

Make sure the target module has unit / integration tests,
and the tests can be run using `npm test` command.

Run `next-update` from the command line in the same folder as
the target module. In general this tool does the following:

1. Reads the module's dependencies (including dev) and their versions
2. Queries npm registry to see if there are newer versions
3. For each dependency that has newer versions available:
    1. Installs each version
    2. Runs command `npm test` to determine if the new version breaks the tests
    3. Installs back the current version.
4. Reports results

### Misc

* To see what has changed in the latest version of any module,
use my companion tool [changed](https://npmjs.org/package/changed)
like this `changed foo` (*foo* is package name)
* When comparing versions, keywords *latest* and *** are both assumed to equal to "0.0.0".
* A good workflow using *next-update*
    * see available new versions `next-update --available`
    * check latest version of each module using `next-update --latest`
    * install new versions of the desired modules using standard `npm i dependency@version --save`
* You can use custom test command, for example `next-update -t "grunt test"`
    * `npm test` is used by default.
* You can keep each working version in package.json by using `--keep` flag.