Part of work on [#101077](https://github.com/flutter/flutter/pull/141194). This is done as a separate PR to avoid a massive diff.
## Context
1. The `FakeCommand` class accepts a list of patterns that's used to match a command given to its `FakeProcessManager`. Since `FakeCommand` can match a list of patterns, not just specifically strings, it can be used to match commands where the exact value of some arguments can't (easily) known ahead of time. For example, a part of the tool may invoke a command with an argument that is the path of a temporarily file that has a randomly-generated basename.
2. The `FakeCommand` class provides on `onRun` parameter, which is a callback that is run when the `FakeProcessManager` runs a command that matches the `FakeCommand` in question.
## Issue
In the event that a `FakeCommand` is constructed using patterns, the test code can't know the exact values used for arguments in the command. This PR proposes changing the type of `onRun` from `VoidCallback?` to `void Function(List<String>)?`. When run, the value `List<String>` parameter will be the full command that the `FakeCommand` matched.
Example:
```dart
FakeCommand(
command: <Pattern>[
artifacts.getArtifactPath(Artifact.engineDartBinary),
'run',
'vector_graphics_compiler',
RegExp(r'--input=/.*\.temp'),
RegExp(r'--output=/.*\.temp'),
],
onRun: (List<String> command) {
final outputPath = (() {
// code to parse `--output` from `command`
})();
testFileSystem.file(outputPath).createSync(recursive: true);
},
)
```
Use the pub cache resolved by pub itself.
To add packages to the flutter.zip download they are packaged as tar.gz and added to the pub-cache on first run by using `pub cache preload`.
* Align `flutter pub get/upgrade/add/remove/downgrade`
* Add final . to command description
* Remove trailing whitespace
* Don't print message that command is being run
* Update expectations
* Use relative path
* Remove duplicated line
* Improve function dartdoc
* Make pub get runner respect printProgress and retry parameters
* Fix typo
* Add regression test
* Improve test
* Fix implementation and test
* Test to fix flutter_drone tests
* Revert test
* Attempt #2 to fix flutter_drone tests
* Revert attempt
* Hack: Force printProgress to debug Windows tests
* Use ProcessUtils.run to avoid dangling stdout and stderr
* Update documentation
* Clean up retry argument
* Removes retries from "pub get" and proxies its stdout output
* Fix issue where ErrorHandlingProcessManager does not forward "mode" parameter to backing ProcessManager's "start" method
* Make "pub get" use ProcessStartMode.inheritStdio instead of forwarding bytes to stdout and stderr
* Fix tests
* Remove unused env var
* Add back 'Running "flutter pub get"...' status log
* Fix indent
* Add Pub.test() constructor which lets tests mock stdio
* Use `dart __deprecated_pub` instead of `pub` to invoke pub from tools
The top level `pub` commmand has been deprecated and will print
a message. It is however implemented via the __deprecated_pub command
that prints no message.
