README for the felt tool (#12323)

Author: mdebbar

lib/web_ui/dev/README.md

@@ -0,0 +1,22 @@
+## What's `felt`?
+`felt` stands for "Flutter Engine Local Tester". It's a cli tool that aims to make development in the Flutter web engine more productive and pleasant.
+
+## What can `felt` do?
+`felt` supports multiple commands as follows:
+
+1. **`felt check-licenses`**: Checks that all Dart and JS source code files contain the correct license headers.
+2. **`felt test`**: Runs all or some tests depending on the passed arguments.
+3. **`felt build`**: Builds the engine locally so it can be used by Flutter apps. It also supports a watch mode for more convenience.
+
+You could also run `felt help` or `felt help <command>` to get more information about the available commands and arguments.
+
+## How can I use `felt`?
+Once you have your local copy of the engine [setup](https://github.com/flutter/flutter/wiki/Setting-up-the-Engine-development-environment), you'll need to add `/path/to/engine/src/flutter/lib/web_ui/dev` to your `PATH`.
+Then you would be able to use the `felt` tool from anywhere:
+```
+felt check-licenses
+```
+or:
+```
+felt build --watch
+```

lib/web_ui/dev/felt

@@ -45,4 +45,10 @@ then
   ninja -C $HOST_DEBUG_UNOPT_DIR
 fi
 
+echo "Running \`pub get\` in 'engine/src/flutter/lib/web_ui'"
+(cd "$WEB_UI_DIR"; $DART_SDK_DIR/bin/pub get)
+
+echo "Running \`pub get\` in 'engine/src/flutter/web_sdk/web_engine_tester'"
+(cd "$FLUTTER_DIR/web_sdk/web_engine_tester"; $DART_SDK_DIR/bin/pub get)
+
 $DART_SDK_DIR/bin/dart "$DEV_DIR/felt.dart" $@