The `LibraryInstallerTest::testUninstall()` method mocks a `Package` object, but did not set an expectation for a call to `getName()`, while that method _is_ called in the `LibraryInstaller::uninstall()` method.
Without expectation, the mock returns `null`, which was subsequently being passed on to `strpos()` leading to the below error.
Fixes:
```
Deprecation triggered by Composer\Test\Installer\LibraryInstallerTest::testUninstall:
strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated
Stack trace:
0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 202)
1 src/Composer/Installer/LibraryInstaller.php(202): strpos(NULL, '...')
2 vendor/react/promise/src/FulfilledPromise.php(28): Composer\Installer\LibraryInstaller->Composer\Installer\{closure}(NULL)
3 src/Composer/Installer/LibraryInstaller.php(208): React\Promise\FulfilledPromise->then(Object(Closure))
4 tests/Composer/Test/Installer/LibraryInstallerTest.php(221): Composer\Installer\LibraryInstaller->uninstall(Object(Mock_InstalledRepositoryInterface_e3699f95), Object(Mock_Package_e4571076))
...
```
The functionality to install binaries might be useful
for other installers.
Create API for that by extracting this functionality from
the LibraryInstaller class.
any tests that use the filesystem should have their own unique directory, as we run our test suite in parallel and
cleanup of tests (removing directories) should not interfere with currently running tests
Add PearInstaller
Change PEAR packages type from 'library' to 'pear-library' and dist type from 'pear' to 'file'
Remove PearDownloader
Refactor Channel Installer