Support legacy way of specifying constraint files (and expand constraint files too) (#1823)

Signed-off-by: Bernát Gábor <bgabor8@bloomberg.net>

1 files changed, 10 insertions, 6 deletions

diff --git a/src/tox/tox_env/python/req_file.py b/src/tox/tox_env/python/req_file.py
index 3a035273..2796e492 100644
--- a/src/tox/tox_env/python/req_file.py
+++ b/src/tox/tox_env/python/req_file.py
@@ -58,10 +58,14 @@ class RequirementsFile:
 
     def __init__(self, raw: str, allow_short_req_file: bool = True, root: Optional[Path] = None) -> None:
         self._root = Path().cwd() if root is None else root
-        if allow_short_req_file:  # patch tox supporting requirements files via -rrequirements.txt
-            r = ((f"-r {i[2:]}" if len(i) >= 3 and i.startswith("-r") and i[2] != " " else i) for i in raw.splitlines())
-            adjusted = "\n".join(r)
-            raw = f"{adjusted}\n" if raw.endswith("\\\n") else adjusted
+        if allow_short_req_file:  # patch for tox<4 supporting requirement/constraint files via -rreq.txt/-creq.txt
+            lines: List[str] = []
+            for line in raw.splitlines():
+                if len(line) >= 3 and (line.startswith("-r") or line.startswith("-c")) and not line[2].isspace():
+                    line = f"{line[:2]} {line[2:]}"
+                lines.append(line)
+            adjusted = "\n".join(lines)
+            raw = f"{adjusted}\n" if raw.endswith("\\\n") else adjusted  # preserve trailing newline if input has it
         self._raw = raw
 
     def __str__(self) -> str:
@@ -93,8 +97,8 @@ class RequirementsFile:
                     if len(words) != 2:
                         raise ValueError(line)
                     else:
-                        if first == "-r":
-                            path = Path(line[3:].strip())
+                        if first in ("-r", "--requirement", "-c", "--constraint"):
+                            path = Path(line[len(first) + 1 :].strip())
                             if not path.is_absolute():
                                 path = ini_dir / path
                             req_file = RequirementsFile(path.read_text(), allow_short_req_file=False, root=self.root)