JSON impl for DummyStore

src/libstore-tests/data/dummy-store/empty.json

@@ -0,0 +1,5 @@
+{
+  "build-trace": {},
+  "contents": {},
+  "store-dir": "/nix/store"
+}

src/libstore-tests/data/dummy-store/one-flat-file.json

@@ -0,0 +1,34 @@
+{
+  "build-trace": {},
+  "contents": {
+    "5hizn7xyyrhxr0k2magvxl5ccvk0ci9n-my-file": {
+      "contents": {
+        "contents": "asdf",
+        "executable": false,
+        "type": "regular"
+      },
+      "info": {
+        "ca": {
+          "hash": {
+            "algorithm": "sha256",
+            "format": "base64",
+            "hash": "f1eduuSIYC1BofXA1tycF79Ai2NSMJQtUErx5DxLYSU="
+          },
+          "method": "nar"
+        },
+        "deriver": null,
+        "narHash": {
+          "algorithm": "sha256",
+          "format": "base64",
+          "hash": "f1eduuSIYC1BofXA1tycF79Ai2NSMJQtUErx5DxLYSU="
+        },
+        "narSize": 120,
+        "references": [],
+        "registrationTime": null,
+        "signatures": [],
+        "ultimate": false
+      }
+    }
+  },
+  "store-dir": "/nix/store"
+}

src/libstore-tests/dummy-store.cc

@@ -1,11 +1,32 @@
 #include <gtest/gtest.h>
+#include <nlohmann/json.hpp>
 
+#include "nix/util/memory-source-accessor.hh"
 #include "nix/store/dummy-store-impl.hh"
 #include "nix/store/globals.hh"
 #include "nix/store/realisation.hh"
 
+#include "nix/util/tests/json-characterization.hh"
+
 namespace nix {
 
+class DummyStoreTest : public virtual CharacterizationTest
+{
+    std::filesystem::path unitTestData = getUnitTestData() / "dummy-store";
+
+public:
+
+    std::filesystem::path goldenMaster(std::string_view testStem) const override
+    {
+        return unitTestData / testStem;
+    }
+
+    static void SetUpTestSuite()
+    {
+        initLibStore(false);
+    }
+};
+
 TEST(DummyStore, realisation_read)
 {
     initLibStore(/*loadConfig=*/false);
@@ -35,4 +56,66 @@ TEST(DummyStore, realisation_read)
     EXPECT_EQ(*value2, value);
 }
 
+/* ----------------------------------------------------------------------------
+ * JSON
+ * --------------------------------------------------------------------------*/
+
+using nlohmann::json;
+
+struct DummyStoreJsonTest : DummyStoreTest,
+                            JsonCharacterizationTest<ref<DummyStore>>,
+                            ::testing::WithParamInterface<std::pair<std::string_view, ref<DummyStore>>>
+{};
+
+TEST_P(DummyStoreJsonTest, from_json)
+{
+    auto & [name, expected] = GetParam();
+    using namespace nlohmann;
+    /* Cannot use `readJsonTest` because need to dereference the stores
+       for equality. */
+    readTest(Path{name} + ".json", [&](const auto & encodedRaw) {
+        auto encoded = json::parse(encodedRaw);
+        ref<DummyStore> decoded = adl_serializer<ref<DummyStore>>::from_json(encoded);
+        ASSERT_EQ(*decoded, *expected);
+    });
+}
+
+TEST_P(DummyStoreJsonTest, to_json)
+{
+    auto & [name, value] = GetParam();
+    writeJsonTest(name, value);
+}
+
+INSTANTIATE_TEST_SUITE_P(DummyStoreJSON, DummyStoreJsonTest, [] {
+    initLibStore(false);
+    auto writeCfg = make_ref<DummyStore::Config>(DummyStore::Config::Params{});
+    writeCfg->readOnly = false;
+    return ::testing::Values(
+        std::pair{
+            "empty",
+            make_ref<DummyStore::Config>(DummyStore::Config::Params{})->openDummyStore(),
+        },
+        std::pair{
+            "one-flat-file",
+            [&] {
+                auto store = writeCfg->openDummyStore();
+                store->addToStore(
+                    "my-file",
+                    SourcePath{
+                        [] {
+                            auto sc = make_ref<MemorySourceAccessor>();
+                            sc->root = MemorySourceAccessor::File{MemorySourceAccessor::File::Regular{
+                                .executable = false,
+                                .contents = "asdf",
+                            }};
+                            return sc;
+                        }(),
+                    },
+                    ContentAddressMethod::Raw::NixArchive,
+                    HashAlgorithm::SHA256);
+                return store;
+            }(),
+        });
+}());
+
 } // namespace nix

src/libstore/dummy-store.cc

@@ -2,6 +2,7 @@
 #include "nix/util/archive.hh"
 #include "nix/util/callback.hh"
 #include "nix/util/memory-source-accessor.hh"
+#include "nix/util/json-utils.hh"
 #include "nix/store/dummy-store-impl.hh"
 #include "nix/store/realisation.hh"
 
@@ -16,6 +17,16 @@ std::string DummyStoreConfig::doc()
         ;
 }
 
+bool DummyStore::PathInfoAndContents::operator==(const PathInfoAndContents & other) const
+{
+    return info == other.info && contents->root == other.contents->root;
+}
+
+bool DummyStore::operator==(const DummyStore & other) const
+{
+    return contents == other.contents && buildTrace == other.buildTrace;
+}
+
 namespace {
 
 class WholeStoreViewAccessor : public SourceAccessor
@@ -378,3 +389,78 @@ ref<DummyStore> DummyStore::Config::openDummyStore() const
 static RegisterStoreImplementation<DummyStore::Config> regDummyStore;
 
 } // namespace nix
+
+namespace nlohmann {
+
+using namespace nix;
+
+DummyStore::PathInfoAndContents adl_serializer<DummyStore::PathInfoAndContents>::from_json(const json & json)
+{
+    auto & obj = getObject(json);
+    return DummyStore::PathInfoAndContents{
+        .info = valueAt(obj, "info"),
+        .contents = make_ref<MemorySourceAccessor>(valueAt(obj, "contents")),
+    };
+}
+
+void adl_serializer<DummyStore::PathInfoAndContents>::to_json(json & json, const DummyStore::PathInfoAndContents & val)
+{
+    json = {
+        {"info", val.info},
+        {"contents", *val.contents},
+    };
+}
+
+ref<DummyStore> adl_serializer<ref<DummyStore>>::from_json(const json & json)
+{
+    auto & obj = getObject(json);
+    ref<DummyStore> res = [&] {
+        auto cfg = make_ref<DummyStore::Config>(DummyStore::Config::Params{});
+        const_cast<PathSetting &>(cfg->storeDir_).set(getString(valueAt(obj, "store-dir")));
+        cfg->readOnly = true;
+        return cfg->openDummyStore();
+    }();
+    for (auto & [k, v] : getObject(valueAt(obj, "contents")))
+        res->contents.insert({StorePath{k}, v});
+    for (auto & [k0, v] : getObject(valueAt(obj, "build-trace"))) {
+        for (auto & [k1, v2] : getObject(v)) {
+            auto vref = make_ref<UnkeyedRealisation>(v2);
+            res->buildTrace.insert_or_visit(
+                {
+                    Hash::parseExplicitFormatUnprefixed(k0, HashAlgorithm::SHA256, HashFormat::Base64),
+                    {{k1, vref}},
+                },
+                [&](auto & kv) { kv.second.insert_or_assign(k1, vref); });
+        }
+    }
+    return res;
+}
+
+void adl_serializer<ref<DummyStore>>::to_json(json & json, const ref<DummyStore> & val)
+{
+    json = {
+        {"store-dir", val->storeDir},
+        {"contents",
+         [&] {
+             auto obj = json::object();
+             val->contents.cvisit_all([&](const auto & kv) {
+                 auto & [k, v] = kv;
+                 obj[k.to_string()] = v;
+             });
+             return obj;
+         }()},
+        {"build-trace",
+         [&] {
+             auto obj = json::object();
+             val->buildTrace.cvisit_all([&](const auto & kv) {
+                 auto & [k, v] = kv;
+                 auto & obj2 = obj[k.to_string(HashFormat::Base64, false)] = json::object();
+                 for (auto & [k2, v2] : kv.second)
+                     obj2[k2] = *v2;
+             });
+             return obj;
+         }()},
+    };
+}
+
+} // namespace nlohmann

src/libstore/include/nix/store/dummy-store-impl.hh

@@ -23,6 +23,8 @@ struct DummyStore : virtual Store
     {
         UnkeyedValidPathInfo info;
         ref<MemorySourceAccessor> contents;
+
+        bool operator==(const PathInfoAndContents &) const;
     };
 
     /**
@@ -54,6 +56,14 @@ struct DummyStore : virtual Store
         , config(config)
     {
     }
+
+    bool operator==(const DummyStore &) const;
 };
 
+template<>
+struct json_avoids_null<DummyStore::PathInfoAndContents> : std::true_type
+{};
+
 } // namespace nix
+
+JSON_IMPL(nix::DummyStore::PathInfoAndContents)

src/libstore/include/nix/store/dummy-store.hh

@@ -2,6 +2,7 @@
 ///@file
 
 #include "nix/store/store-api.hh"
+#include "nix/util/json-impls.hh"
 
 #include <boost/unordered/concurrent_flat_map.hpp>
 
@@ -65,4 +66,10 @@ struct DummyStoreConfig : public std::enable_shared_from_this<DummyStoreConfig>,
     }
 };
 
+template<>
+struct json_avoids_null<ref<nix::DummyStore>> : std::true_type
+{};
+
 } // namespace nix
+
+JSON_IMPL(nix::ref<nix::DummyStore>)