test: cover ArxBuilder link and link_mode paths

tests/test_codegen_file_object.py

@@ -5,7 +5,9 @@
 import shutil
 
 from pathlib import Path
+from typing import Any, Literal, cast
 
+import astx
 import pytest
 
 from arx.codegen import ArxBuilder
@@ -17,6 +19,23 @@
 TMP_PATH.mkdir(exist_ok=True)
 HAS_CLANG = shutil.which("clang") is not None
 
+_MIN_FLOAT_MAIN = "fn main() -> f32:\n  return 1.0 + 1.0\n"
+
+
+def _parse_min_module(code: str = _MIN_FLOAT_MAIN) -> astx.Module:
+    """
+    title: Parse a minimal one-line main module for codegen tests.
+    parameters:
+      code:
+        type: str
+    returns:
+      type: astx.Module
+    """
+    ArxIO.string_to_buffer(code)
+    tree = Parser().parse(Lexer().lex())
+    assert isinstance(tree, astx.Module)
+    return tree
+
 
 @pytest.mark.parametrize(
     "code",
@@ -44,3 +63,93 @@ def test_object_generation(code: str) -> None:
     bin_path = TMP_PATH / "testtmp"
     ir.build(module_ast, str(bin_path))
     bin_path.unlink()
+
+
+def test_build_without_link_writes_object_bytes(
+    tmp_path: Path,
+) -> None:
+    """
+    title: link=False writes the LLVM object to output_file and skips clang.
+    parameters:
+      tmp_path:
+        type: Path
+    """
+    module_ast = _parse_min_module()
+    out = tmp_path / "only.o"
+    ArxBuilder().build(module_ast, str(out), link=False)
+    assert out.is_file()
+    assert out.stat().st_size > 0
+
+
+def test_build_rejects_unknown_link_mode(tmp_path: Path) -> None:
+    """
+    title: Unknown link_mode raises before invoking the linker.
+    parameters:
+      tmp_path:
+        type: Path
+    """
+    module_ast = _parse_min_module()
+    invalid: Any = "not-a-link-mode"
+    with pytest.raises(ValueError, match="Invalid link mode"):
+        ArxBuilder().build(
+            module_ast,
+            str(tmp_path / "never"),
+            link=True,
+            link_mode=invalid,
+        )
+
+
+@pytest.mark.parametrize(
+    ("mode", "expect_flag"),
+    [
+        ("pie", "-pie"),
+        ("no-pie", "-no-pie"),
+    ],
+)
+@pytest.mark.skipif(not HAS_CLANG, reason="clang is required for object build")
+def test_build_passes_explicit_link_flags(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+    mode: str,
+    expect_flag: str,
+) -> None:
+    """
+    title: pie and no-pie link modes forward the matching flag to clang.
+    parameters:
+      tmp_path:
+        type: Path
+      monkeypatch:
+        type: pytest.MonkeyPatch
+      mode:
+        type: str
+      expect_flag:
+        type: str
+    """
+    module_ast = _parse_min_module()
+    exe = tmp_path / f"out-{mode}"
+    recorded: dict[str, object] = {}
+
+    def fake_clang(*args: object, **_kwargs: object) -> None:
+        """
+        title: Record clang argv and create the declared output artifact.
+        parameters:
+          args:
+            type: object
+            variadic: positional
+          _kwargs:
+            type: object
+            variadic: keyword
+        """
+        recorded["args"] = args
+        Path(str(args[-1])).write_bytes(b"")
+
+    monkeypatch.setattr("arx.codegen.xh.clang", fake_clang)
+
+    link_mode = cast(Literal["auto", "pie", "no-pie"], mode)
+    ArxBuilder().build(module_ast, str(exe), link=True, link_mode=link_mode)
+
+    args_tuple = recorded["args"]
+    assert isinstance(args_tuple, tuple)
+    assert expect_flag in args_tuple
+    assert args_tuple[-1] == str(exe)
+    assert exe.is_file()