- [x] Have you followed the guidelines for contributing? - [x] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [x] Have you successfully run `make lint && make test`? --- Implements the `progress_bar` method for the emitter. This one has an entirely different API from the existing one, but comes with far more content. The exact appearance of the progress bar doesn't need much review, as the design team and I have not landed on an approved appearance yet. I strongly recommend reviewing per-commit. Here's a script that showcases some of the new behavior and gives a good starting point for testing by hand: ```py import logging from time import sleep from craft_cli import Emitter, Verbosity logger = logging.getLogger(__name__) logger.setLevel(logging.DEBUG) e = Emitter(Verbosity.BRIEF, "blah.log", "Hello", streaming_brief=True) logger.info("Testing") TOTAL_NUMBERS = 50 with e.progress_bar("Crunching the numbers", TOTAL_NUMBERS, show_progress=True, show_percentage=True) as prog: # An overflow just keeps counting over the total. for i in range(TOTAL_NUMBERS + 10): prog.tick() sleep(0.1) if i % 25 == 0: logger.warning("⚠️ Booping imminent ⚠️") sleep(0.1) prog.println("Boop") # Can't increment with a negative try: prog.inc(-1) except OverflowError as err: prog.println(f"Caught: {err}") prog.println("Phew, that was close.") # Can't use emitter methods while progress bar is active try: e.message("MOM SAID IT'S MY TURN WITH THE TTY") except RuntimeError as err: prog.println(f"Caught: {err}") prog.println("I get one more CPU cycle!") e.message("Done") ``` CRAFT-4983