coursier: additional_dependencies support

testing/language_helpers.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+import os
+from typing import Sequence
+
+import pre_commit.constants as C
+from pre_commit.languages.all import Language
+from pre_commit.prefix import Prefix
+
+
+def run_language(
+        path: os.PathLike[str],
+        language: Language,
+        exe: str,
+        args: Sequence[str] = (),
+        file_args: Sequence[str] = (),
+        version: str = C.DEFAULT,
+        deps: Sequence[str] = (),
+) -> tuple[int, bytes]:
+    prefix = Prefix(str(path))
+
+    language.install_environment(prefix, version, deps)
+    with language.in_env(prefix, version):
+        ret, out = language.run_hook(
+            prefix,
+            exe,
+            args,
+            file_args,
+            require_serial=True,
+            color=False,
+        )
+        out = out.replace(b'\r\n', b'\n')
+        return ret, out