Improve error messages for downloading UF2s

circfirm/backend/cache.py

@@ -48,7 +48,9 @@ def download_uf2(board_id: str, version: str, language: str = "en_US") -> None:
 
     SUCCESS = 200
     if response.status_code != SUCCESS:
-        raise ConnectionError(f"Could not download the specified UF2 file:\n{url}")
+        raise ConnectionError(
+            f"Could not download the specified UF2 file:\n{url}\nAre the board ID, version, and language correct?"
+        )
 
     uf2_file.parent.mkdir(parents=True, exist_ok=True)
     with open(uf2_file, mode="wb") as uf2file:

pyproject.toml

@@ -86,5 +86,6 @@ ignore = ["D213", "D203"]
 [tool.pytest.ini_options]
 filterwarnings = ["ignore:datetime.datetime.utcfromtimestamp():DeprecationWarning"]
 addopts = [
-    "--ignore=tests/sandbox/circuitpython"
+    "--ignore=tests/sandbox/circuitpython",
+    "--ignore=tests/backup",
 ]

tests/cli/test_cli_cache.py

@@ -88,6 +88,7 @@ def test_cache_save() -> None:
         "https://downloads.circuitpython.org/bin/feather_m4_express/"
         "nolanguage/"
         "adafruit-circuitpython-feather_m4_express-nolanguage-7.3.0.uf2\n"
+        "Are the board ID, version, and language correct?\n"
     )