* readall: move readall logic to new class.

* tap: run readall when tapping.

This will prevent tapping an tap with syntax errors from causing issues
for users.

Fixes #58.

Including the extension is not an error, but we don't normally do this.

Instead of writing a custom ensure for every test let's just nuke
all the files every time. This may be something we might want to use for
other unit tests too. It leans heavily on the fact that a
`FileUtils.rm_rf` on files that don't exist is very quick and things
like `brew cleanup` are super slow in comparison.

Before:
```
$ brew tests --only=integration_cmds --official-cmd-taps
Finished in 49.764724s, 1.0047 runs/s, 5.2648 assertions/s.
```

After:
```
$ brew tests --only=integration_cmds --official-cmd-taps
Finished in 43.014769s, 1.1624 runs/s, 5.8352 assertions/s.
```

The `build` and `source_modified_time` arguments are always coming from
the matching attributes of the `Formula` instance. Thus query `formula`
for them instead of passing them individually.

This reverts commit 080ddd88.

This reverts commit 310d7067.

* Don't infinitely recurse `brew update --preinstall`.

This could happen when trying to `brew install git` inside `brew update
--preinstall`.

* update.sh: cache Git PATH.

We don’t need to look it up from superenv every time; this is slow.

* update.sh: print message before preinstall updates.

* update.sh: verbose output fetch directory.

This aids reading `brew update --verbose --debug` output.

* update.sh: skip taps without formulae on preinstall.

We don’t need to update them as we’re not invoking them.

* update.sh: don't force update-report on developer preinstall.

This is too slow.

The length of the commit hash returned for `--short` can vary depending
on user configuration. Make sure this works independently of what might
have been configured via a user's `.gitconfig`. This also fixes the
failing `GitDownloadStrategyTests#test_last_commit` test for such users.

Closes #464.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

Add an extension for accessing Git-related meta data that can be mixed
in into a Pathname object (e.g. `HOMBREW_REPOSITORY` or the path of a
`Tap` instance). The goal here is to eliminate code duplication.

Remove an exact duplicate from further up in the same file. (It was
accidentally added in 8a582f2b.)

Closes #460.

Signed-off-by: Xu Cheng <xucheng@me.com>

Implement:
  * VCSDownloadStrategy#last_commit
    Use last modified file timestamp
  * SubversionDownloadStrategy#last_commit
    Use `svn info --show-item revision`
  * GitDownloadStrategy#last_commit
    Use `git rev-parse HEAD`
  * MercurialDownloadStrategy#last_commit
    Use `hg parent --template {node}`
  * BazaarDownloadStrategy#last_commit
    Use `bazaar revno`
  * FossilDownloadStrategy#last_commit
  Use `fossil info tip`

Closes https://github.com/Homebrew/homebrew-core/issues/2758

Beta versions of XQuartz have address sanitization enabled, which
breaks some software at runtime, including wine.

Closes Homebrew/homebrew-core#2481.

Closes #459.

Signed-off-by: Misty De Meo <mistydemeo@github.com>

Rearrange path constants such that persistent paths (that point into the
Homebrew code base) are in one spot and all other paths (that are being
redirected to a temporary location for the duration of the test run) are
grouped together.

Closes #440.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

Truncates each log file to about 1 MB. This avoids upload and
download errors with the gists, and respects GitHub's suggested
size limits.

Prior to the fix, every run of the test suite would leave behind a pair
of empty directories in `$TMPDIR`. (A temporary home directory was
created but only its child `Applications` was wiped when done.)

This reverts commit dba1958b.

This reverts commit 252c701c.

Taps installed prior to running the test suite are not visible to the
test suite as most Homebrew paths are redefined as to not mess up the
local installation.

Since we've moved all formulae to taps it's not necessarily obvious
what the path for the files are otherwise.

All of these taps use Homebrew internal APIs (or will shortly) and we
autoinstall them all from `brew $CMD`. We should adjust our CI to ensure
that we never accidentally break these taps when making changes to core
code so that these taps can rely more on this core code rather than
having to e.g. vendor equivalent code that never changes on our end.

This is a developer-only option I created for testing purposes. It
should not be used by end-users.