add argument for noxfile to install from an sdist

noxfile.py

@@ -1,3 +1,4 @@
+import os
 import pathlib
 import shutil
 import sys
@@ -11,10 +12,19 @@
 @nox.session(name="test-with-pip", python=["3.10", "3.11", "3.12"])
 def test_with_pip(session: nox.Session) -> None:
     """Run the tests."""
+    first_arg = session.posargs[0] if session.posargs else None
+
     session.install("-r", "requirements-testing.in")
     if sys.platform.startswith("win"):
         session.install("ecmwflibs")
-    session.install(".")
+
+    if first_arg:
+        if os.path.isfile(first_arg):
+            session.install(first_arg)
+        else:
+            session.error("path must be a source distribution")
+    else:
+        session.install(".")
 
     session.run("pytest", "--cov=src/bmi_wavewatch3", "-vvv")
     session.run("coverage", "report", "--ignore-errors", "--show-missing")
@@ -26,9 +36,18 @@ def test_with_pip(session: nox.Session) -> None:
 )
 def test_with_conda(session: nox.Session) -> None:
     """Run the tests."""
+    first_arg = session.posargs[0] if session.posargs else None
+
     session.conda_install("--file=requirements-testing.in")
     session.conda_install("--file=requirements-conda.in")
-    session.install(".", "--no-deps")
+
+    if first_arg:
+        if os.path.isfile(first_arg):
+            session.install(first_arg, "--no-deps")
+        else:
+            session.error("path must be a source distribution")
+    else:
+        session.install(".", "--no-deps")
 
     session.run("pytest", "--cov=src/bmi_wavewatch3", "-vvv")
     session.run("coverage", "report", "--ignore-errors", "--show-missing")