tests: add regression tests for positional-only sampler init bindings

Covers the seven bindings fixed for #2371: each gets a test confirming
a keyword call that's short on positional arguments is rejected
outright with TypeError.

Also adds one test documenting a related but unfixed case: once every
positional slot is already filled, ctypes silently ignores an extra
keyword instead of raising. Positional-only marking can't close that,
since there's no unfilled slot left for it to protect.

Author: Belal0066

tests/test_llama_cpp.py

@@ -0,0 +1,51 @@
+import pytest
+
+import llama_cpp
+
+# ctypes function objects built without paramflags bind arguments
+# positionally only; the trailing `/` on these bindings just keeps the
+# type stub honest about that (#2371).
+
+
+def test_llama_sampler_init_dist_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_dist(seed=0)
+
+
+def test_llama_sampler_init_top_k_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_top_k(k=40)
+
+
+def test_llama_sampler_init_top_p_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_top_p(0.9, min_keep=1)
+
+
+def test_llama_sampler_init_min_p_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_min_p(0.1, min_keep=1)
+
+
+def test_llama_sampler_init_typical_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_typical(1.0, min_keep=1)
+
+
+def test_llama_sampler_init_temp_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_temp(t=0.8)
+
+
+def test_llama_sampler_init_temp_ext_rejects_keyword_args():
+    with pytest.raises(TypeError):
+        llama_cpp.llama_sampler_init_temp_ext(0.8, 0.0, exponent=1.0)
+
+
+def test_llama_sampler_init_top_p_silently_ignores_extra_keyword():
+    # Known limitation, not fixed here: with all positional slots filled,
+    # ctypes has no parameter names to match an extra keyword against, so
+    # it's silently ignored instead of raising.
+    sampler = llama_cpp.llama_sampler_init_top_p(0.9, 1, bogus=999)
+    assert sampler
+    llama_cpp.llama_sampler_free(sampler)