feat(solver-bootstrap): step 0 — harness-self-tests

tests/harness/test_discovery.py

@@ -0,0 +1,30 @@
+import pytest
+
+from scripts.msvc_harness.config import load_config
+from scripts.msvc_harness.discovery import DiscoveryError, discover_project
+from scripts.msvc_harness.models import ProjectKind
+
+
+def test_discover_project_skips_empty_repository(tmp_path):
+    result = discover_project(tmp_path, load_config(tmp_path))
+
+    assert result.selection is None
+
+
+def test_discover_project_prefers_cmake(tmp_path):
+    cmake_lists = tmp_path / "CMakeLists.txt"
+    cmake_lists.write_text("cmake_minimum_required(VERSION 3.25)\n", encoding="utf-8")
+    (tmp_path / "fallback.sln").write_text("", encoding="utf-8")
+
+    result = discover_project(tmp_path, load_config(tmp_path))
+
+    assert result.selection is not None
+    assert result.selection.kind is ProjectKind.CMAKE
+    assert result.selection.project_file == cmake_lists
+
+
+def test_discover_project_rejects_orphan_cpp_project(tmp_path):
+    (tmp_path / "orphan.cpp").write_text("int value = 0;\n", encoding="utf-8")
+
+    with pytest.raises(DiscoveryError, match="C/C\\+\\+ files exist"):
+        discover_project(tmp_path, load_config(tmp_path))