[M1] add layout::discover

tests/layout_discovery.cpp

@@ -0,0 +1,193 @@
+#include <catch2/catch_test_macros.hpp>
+
+import cargoxx.layout;
+import cargoxx.util;
+import std;
+
+using cargoxx::layout::DiscoveredLayout;
+using cargoxx::layout::discover;
+using cargoxx::layout::Target;
+using cargoxx::layout::TargetKind;
+using cargoxx::util::ErrorCode;
+
+namespace {
+
+class TempProject {
+  public:
+    TempProject() {
+        root_ = std::filesystem::temp_directory_path() /
+                std::format("cargoxx-layout-test-{}", std::random_device{}());
+        std::filesystem::create_directories(root_);
+    }
+
+    ~TempProject() {
+        std::error_code ec;
+        std::filesystem::remove_all(root_, ec);
+    }
+
+    TempProject(const TempProject&) = delete;
+    TempProject& operator=(const TempProject&) = delete;
+    TempProject(TempProject&&) = delete;
+    TempProject& operator=(TempProject&&) = delete;
+
+    auto root() const -> const std::filesystem::path& { return root_; }
+
+    auto touch(std::string_view rel) -> std::filesystem::path {
+        auto p = root_ / rel;
+        std::filesystem::create_directories(p.parent_path());
+        std::ofstream{p} << "// stub\n";
+        return p;
+    }
+
+  private:
+    std::filesystem::path root_;
+};
+
+} // namespace
+
+TEST_CASE("discover returns LayoutNoTarget for an empty src", "[layout]") {
+    TempProject p;
+    std::filesystem::create_directories(p.root() / "src");
+    auto r = discover(p.root(), "foo");
+    REQUIRE_FALSE(r.has_value());
+    REQUIRE(r.error().code == ErrorCode::LayoutNoTarget);
+}
+
+TEST_CASE("discover finds main.cpp as a binary", "[layout]") {
+    TempProject p;
+    auto main = p.touch("src/main.cpp");
+    auto r = discover(p.root(), "foo");
+    REQUIRE(r.has_value());
+    REQUIRE_FALSE(r->library.has_value());
+    REQUIRE(r->binaries.size() == 1);
+    REQUIRE(r->binaries[0].kind == TargetKind::Binary);
+    REQUIRE(r->binaries[0].name == "foo");
+    REQUIRE(r->binaries[0].entry == main);
+}
+
+TEST_CASE("discover finds lib.cppm as a library", "[layout]") {
+    TempProject p;
+    auto lib = p.touch("src/lib.cppm");
+    auto r = discover(p.root(), "foo");
+    REQUIRE(r.has_value());
+    REQUIRE(r->library.has_value());
+    REQUIRE(r->library->kind == TargetKind::Library);
+    REQUIRE(r->library->name == "foo");
+    REQUIRE(r->library->entry == lib);
+    REQUIRE(r->library->module_units == std::vector{lib});
+    REQUIRE(r->library->additional_sources.empty());
+    REQUIRE(r->binaries.empty());
+}
+
+TEST_CASE("discover supports lib + main together", "[layout]") {
+    TempProject p;
+    p.touch("src/lib.cppm");
+    p.touch("src/main.cpp");
+    auto r = discover(p.root(), "foo");
+    REQUIRE(r.has_value());
+    REQUIRE(r->library.has_value());
+    REQUIRE(r->binaries.size() == 1);
+    REQUIRE(r->binaries[0].entry.filename() == "main.cpp");
+}
+
+TEST_CASE("discover collects nested .cppm and .cpp into the library",
+          "[layout]") {
+    TempProject p;
+    auto lib = p.touch("src/lib.cppm");
+    auto inner_cppm = p.touch("src/internal/foo.cppm");
+    auto inner_cpp = p.touch("src/internal/foo.cpp");
+    auto r = discover(p.root(), "foo");
+    REQUIRE(r.has_value());
+    REQUIRE(r->library->module_units.size() == 2);
+    REQUIRE(std::ranges::find(r->library->module_units, lib) !=
+            r->library->module_units.end());
+    REQUIRE(std::ranges::find(r->library->module_units, inner_cppm) !=
+            r->library->module_units.end());
+    REQUIRE(r->library->additional_sources == std::vector{inner_cpp});
+}
+
+TEST_CASE("discover excludes src/bin/* from the library walk", "[layout]") {
+    TempProject p;
+    p.touch("src/lib.cppm");
+    p.touch("src/bin/tool.cpp");
+    auto r = discover(p.root(), "foo");
+    REQUIRE(r.has_value());
+    REQUIRE(r->library->additional_sources.empty());
+    REQUIRE(r->binaries.size() == 1);
+    REQUIRE(r->binaries[0].name == "tool");
+}
+
+TEST_CASE("discover lists src/bin/*.cpp as additional binaries", "[layout]") {
+    TempProject p;
+    p.touch("src/main.cpp");
+    p.touch("src/bin/foo.cpp");
+    p.touch("src/bin/bar.cpp");
+    auto r = discover(p.root(), "pkg");
+    REQUIRE(r.has_value());
+    REQUIRE(r->binaries.size() == 3);
+    // sorted alphabetically by target name
+    REQUIRE(r->binaries[0].name == "bar");
+    REQUIRE(r->binaries[1].name == "foo");
+    REQUIRE(r->binaries[2].name == "pkg");
+}
+
+TEST_CASE("discover does not recurse into src/bin/", "[layout]") {
+    TempProject p;
+    p.touch("src/main.cpp");
+    p.touch("src/bin/foo.cpp");
+    p.touch("src/bin/sub/nested.cpp"); // should be ignored
+    auto r = discover(p.root(), "pkg");
+    REQUIRE(r.has_value());
+    REQUIRE(r->binaries.size() == 2);
+}
+
+TEST_CASE("discover lists tests/*.cpp", "[layout]") {
+    TempProject p;
+    p.touch("src/main.cpp");
+    p.touch("tests/alpha.cpp");
+    p.touch("tests/beta.cpp");
+    p.touch("tests/sub/nested.cpp"); // ignored, no recursion
+    auto r = discover(p.root(), "pkg");
+    REQUIRE(r.has_value());
+    REQUIRE(r->tests.size() == 2);
+    REQUIRE(r->tests[0].name == "alpha");
+    REQUIRE(r->tests[0].kind == TargetKind::Test);
+    REQUIRE(r->tests[1].name == "beta");
+}
+
+TEST_CASE("discover lists examples/*.cpp", "[layout]") {
+    TempProject p;
+    p.touch("src/main.cpp");
+    p.touch("examples/demo.cpp");
+    auto r = discover(p.root(), "pkg");
+    REQUIRE(r.has_value());
+    REQUIRE(r->examples.size() == 1);
+    REQUIRE(r->examples[0].name == "demo");
+    REQUIRE(r->examples[0].kind == TargetKind::Example);
+}
+
+TEST_CASE("discover ignores non .cpp/.cppm files", "[layout]") {
+    TempProject p;
+    p.touch("src/main.cpp");
+    p.touch("src/notes.txt");
+    p.touch("src/lib.cppm");
+    p.touch("src/internal/header.h"); // headers in src/ are ignored
+    auto r = discover(p.root(), "pkg");
+    REQUIRE(r.has_value());
+    REQUIRE(r->library->module_units.size() == 1);
+    REQUIRE(r->library->additional_sources.empty());
+}
+
+TEST_CASE("discover output is deterministic across runs", "[layout]") {
+    TempProject p;
+    p.touch("src/lib.cppm");
+    p.touch("src/zeta.cppm");
+    p.touch("src/alpha.cppm");
+    p.touch("src/middle.cppm");
+    auto r1 = discover(p.root(), "pkg");
+    auto r2 = discover(p.root(), "pkg");
+    REQUIRE(r1.has_value());
+    REQUIRE(r2.has_value());
+    REQUIRE(*r1 == *r2);
+    REQUIRE(std::ranges::is_sorted(r1->library->module_units));
+}