[M5+] add resolver::conan_probe

tests/CMakeLists.txt

@@ -28,3 +28,5 @@ cargoxx_add_test(nixpkgs_probe_parse)
 cargoxx_add_test(nixpkgs_probe_live)
 cargoxx_add_test(nix_cmake_scan_parse)
 cargoxx_add_test(nix_cmake_scan_live)
+cargoxx_add_test(conan_probe_parse)
+cargoxx_add_test(conan_probe_live)

tests/conan_probe_live.cpp

@@ -0,0 +1,41 @@
+// Network-gated integration test for resolver::conan_probe.
+
+#include <catch2/catch_test_macros.hpp>
+
+import cargoxx.resolver;
+import cargoxx.util;
+import std;
+
+namespace {
+
+auto network_tests_enabled() -> bool {
+    auto* env = std::getenv("CARGOXX_NETWORK_TESTS");
+    return env != nullptr && std::string_view{env} == "1";
+}
+
+} // namespace
+
+TEST_CASE("conan_probe finds 'fmt' in conan-center-index",
+          "[resolver][network]") {
+    if (!network_tests_enabled()) {
+        SKIP("CARGOXX_NETWORK_TESTS != 1");
+    }
+    auto r = cargoxx::resolver::conan_probe("fmt");
+    REQUIRE(r.has_value());
+    REQUIRE_FALSE(r->find_package.empty());
+    REQUIRE_FALSE(r->targets.empty());
+    // fmt's recipe should set cmake_target_name = "fmt::fmt".
+    REQUIRE(r->targets.front() == "fmt::fmt");
+}
+
+TEST_CASE("conan_probe returns ResolutionUnknownPackage for a 404",
+          "[resolver][network]") {
+    if (!network_tests_enabled()) {
+        SKIP("CARGOXX_NETWORK_TESTS != 1");
+    }
+    auto r = cargoxx::resolver::conan_probe(
+        "definitely_not_a_real_pkg_cargoxx_xyzzy");
+    REQUIRE_FALSE(r.has_value());
+    REQUIRE(r.error().code ==
+            cargoxx::util::ErrorCode::ResolutionUnknownPackage);
+}

tests/conan_probe_parse.cpp

@@ -0,0 +1,81 @@
+#include <catch2/catch_test_macros.hpp>
+
+import cargoxx.resolver;
+import cargoxx.util;
+import std;
+
+using cargoxx::resolver::parse_conanfile;
+using cargoxx::util::ErrorCode;
+
+TEST_CASE("parse_conanfile picks up modern set_property form", "[resolver][conan]") {
+    constexpr std::string_view text = R"PY(
+from conan import ConanFile
+
+class FmtConan(ConanFile):
+    name = "fmt"
+    def package_info(self):
+        self.cpp_info.set_property("cmake_file_name", "fmt")
+        self.cpp_info.set_property("cmake_target_name", "fmt::fmt")
+)PY";
+
+    auto r = parse_conanfile(text, "fmt");
+    REQUIRE(r.has_value());
+    REQUIRE(r->find_package == "fmt CONFIG REQUIRED");
+    REQUIRE(r->targets == std::vector<std::string>{"fmt::fmt"});
+}
+
+TEST_CASE("parse_conanfile picks up legacy names[] form", "[resolver][conan]") {
+    constexpr std::string_view text = R"PY(
+class SpdlogConan(ConanFile):
+    def package_info(self):
+        self.cpp_info.names["cmake_find_package"] = "spdlog"
+)PY";
+
+    auto r = parse_conanfile(text, "spdlog");
+    REQUIRE(r.has_value());
+    REQUIRE(r->find_package == "spdlog CONFIG REQUIRED");
+    // Derived target heuristic: spdlog::spdlog
+    REQUIRE(r->targets == std::vector<std::string>{"spdlog::spdlog"});
+}
+
+TEST_CASE("parse_conanfile derives cmake_file_name from a colon-namespaced target",
+          "[resolver][conan]") {
+    constexpr std::string_view text = R"PY(
+self.cpp_info.set_property("cmake_target_name", "Boost::filesystem")
+)PY";
+    auto r = parse_conanfile(text, "boost");
+    REQUIRE(r.has_value());
+    REQUIRE(r->find_package == "Boost CONFIG REQUIRED");
+    REQUIRE(r->targets == std::vector<std::string>{"Boost::filesystem"});
+}
+
+TEST_CASE("parse_conanfile falls back to the package name when nothing matches",
+          "[resolver][conan]") {
+    constexpr std::string_view text = R"PY(
+# This recipe gives us nothing useful at the cpp_info level.
+class OpaqueConan(ConanFile):
+    name = "opaque"
+)PY";
+    auto r = parse_conanfile(text, "opaque");
+    REQUIRE(r.has_value());
+    REQUIRE(r->find_package == "opaque CONFIG REQUIRED");
+    REQUIRE(r->targets == std::vector<std::string>{"opaque::opaque"});
+}
+
+TEST_CASE("parse_conanfile errors when no information AND no fallback",
+          "[resolver][conan]") {
+    auto r = parse_conanfile("# nothing here", "");
+    REQUIRE_FALSE(r.has_value());
+    REQUIRE(r.error().code == ErrorCode::ResolutionUnknownPackage);
+}
+
+TEST_CASE("parse_conanfile accepts single-quoted strings", "[resolver][conan]") {
+    constexpr std::string_view text = R"PY(
+self.cpp_info.set_property('cmake_target_name', 'absl::strings')
+self.cpp_info.set_property('cmake_file_name', 'absl')
+)PY";
+    auto r = parse_conanfile(text, "abseil");
+    REQUIRE(r.has_value());
+    REQUIRE(r->find_package == "absl CONFIG REQUIRED");
+    REQUIRE(r->targets == std::vector<std::string>{"absl::strings"});
+}