[vcpkg registries] support versions (#15114)

* [vcpkg registries] support versions

This PR merges the Registries changes and the versioning changes, so that one can use both at the same time.

There is one major difference between this PR and the RFC (#13590), which is that instead of version files looking like:

```json
[
  ...
]
```

version files look like:

```
{
  "versions": [
    ...
  ]
}
```

this is to support interop between this PR and existing demos and the like;
fixing this, along with perhaps renaming `port_versions` to `port-versions` should be done after this is merged,
should be a trivial change.

1 files changed, 132 insertions, 0 deletions

diff --git a/toolsrc/src/vcpkg-test/registries.cpp b/toolsrc/src/vcpkg-test/registries.cpp
new file mode 100644
index 000000000..1c839409d
--- /dev/null
+++ b/toolsrc/src/vcpkg-test/registries.cpp
@@ -0,0 +1,132 @@
+#include <catch2/catch.hpp>
+
+#include <vcpkg/base/jsonreader.h>
+
+#include <vcpkg/registries.h>
+
+using namespace vcpkg;
+
+namespace
+{
+    struct TestRegistryImplementation final : RegistryImplementation
+    {
+        std::unique_ptr<RegistryEntry> get_port_entry(const VcpkgPaths&, StringView) const override { return nullptr; }
+
+        void get_all_port_names(std::vector<std::string>&, const VcpkgPaths&) const override { }
+
+        Optional<VersionT> get_baseline_version(const VcpkgPaths&, StringView) const override { return nullopt; }
+
+        int number;
+
+        TestRegistryImplementation(int n) : number(n) { }
+    };
+
+    Registry make_registry(int n, std::vector<std::string>&& port_names)
+    {
+        return {std::move(port_names), std::make_unique<TestRegistryImplementation>(n)};
+    }
+
+    int get_tri_num(const RegistryImplementation& r)
+    {
+        if (auto tri = dynamic_cast<const TestRegistryImplementation*>(&r))
+        {
+            return tri->number;
+        }
+        else
+        {
+            return -1;
+        }
+    }
+
+    // test functions which parse string literals, so no concerns about failure
+    Json::Value parse_json(StringView sv) { return Json::parse(sv).value_or_exit(VCPKG_LINE_INFO).first; }
+}
+
+TEST_CASE ("registry_set_selects_registry", "[registries]")
+{
+    RegistrySet set;
+    set.set_default_registry(std::make_unique<TestRegistryImplementation>(0));
+
+    set.add_registry(make_registry(1, {"p1", "q1", "r1"}));
+    set.add_registry(make_registry(2, {"p2", "q2", "r2"}));
+
+    auto reg = set.registry_for_port("p1");
+    REQUIRE(reg);
+    CHECK(get_tri_num(*reg) == 1);
+    reg = set.registry_for_port("r2");
+    REQUIRE(reg);
+    CHECK(get_tri_num(*reg) == 2);
+    reg = set.registry_for_port("a");
+    REQUIRE(reg);
+    CHECK(get_tri_num(*reg) == 0);
+
+    set.set_default_registry(nullptr);
+
+    reg = set.registry_for_port("q1");
+    REQUIRE(reg);
+    CHECK(get_tri_num(*reg) == 1);
+    reg = set.registry_for_port("p2");
+    REQUIRE(reg);
+    CHECK(get_tri_num(*reg) == 2);
+    reg = set.registry_for_port("a");
+    CHECK_FALSE(reg);
+}
+
+TEST_CASE ("registry_parsing", "[registries]")
+{
+    Json::Reader r;
+    auto registry_impl_des = get_registry_implementation_deserializer({});
+
+    auto test_json = parse_json(R"json(
+{
+    "kind": "builtin"
+}
+    )json");
+    auto registry_impl = r.visit(test_json, *registry_impl_des);
+    REQUIRE(registry_impl);
+    CHECK(*registry_impl.get());
+    CHECK(r.errors().empty());
+
+    test_json = parse_json(R"json(
+{
+    "kind": "builtin",
+    "baseline": "hi"
+}
+    )json");
+    registry_impl = r.visit(test_json, *registry_impl_des);
+    REQUIRE(registry_impl);
+    CHECK(*registry_impl.get());
+    CHECK(r.errors().empty());
+
+    test_json = parse_json(R"json(
+{
+    "kind": "builtin",
+    "path": "a/b"
+}
+    )json");
+    registry_impl = r.visit(test_json, *registry_impl_des);
+    CHECK_FALSE(r.errors().empty());
+    r.errors().clear();
+
+    test_json = parse_json(R"json(
+{
+    "kind": "filesystem",
+    "path": "a/b/c"
+}
+    )json");
+    registry_impl = r.visit(test_json, *registry_impl_des);
+    REQUIRE(registry_impl);
+    CHECK(*registry_impl.get());
+    CHECK(r.errors().empty());
+
+    test_json = parse_json(R"json(
+{
+    "kind": "filesystem",
+    "path": "/a/b/c"
+}
+    )json");
+    registry_impl = r.visit(test_json, *registry_impl_des);
+    REQUIRE(registry_impl);
+    CHECK(*registry_impl.get());
+    CHECK(r.errors().empty());
+}