Update dummy store JSON format to include derivations

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

@@ -1,5 +1,6 @@
 {
   "build-trace": {},
   "contents": {},
+  "derivations": {},
   "store-dir": "/nix/store"
 }

src/libstore-tests/data/dummy-store/one-derivation.json

@@ -0,0 +1,18 @@
+{
+  "build-trace": {},
+  "contents": {},
+  "derivations": {
+    "rlqjbbb65ggcx9hy577hvnn929wz1aj0-foo.drv": {
+      "args": [],
+      "builder": "",
+      "env": {},
+      "inputDrvs": {},
+      "inputSrcs": [],
+      "name": "foo",
+      "outputs": {},
+      "system": "",
+      "version": 4
+    }
+  },
+  "store-dir": "/nix/store"
+}

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

@@ -30,5 +30,6 @@
       }
     }
   },
+  "derivations": {},
   "store-dir": "/nix/store"
 }

src/libstore-tests/dummy-store.cc

@@ -115,6 +115,16 @@ INSTANTIATE_TEST_SUITE_P(DummyStoreJSON, DummyStoreJsonTest, [] {
                     HashAlgorithm::SHA256);
                 return store;
             }(),
+        },
+        std::pair{
+            "one-derivation",
+            [&] {
+                auto store = writeCfg->openDummyStore();
+                Derivation drv;
+                drv.name = "foo";
+                store->writeDerivation(drv);
+                return store;
+            }(),
         });
 }());
 

src/libstore/dummy-store.cc

@@ -422,6 +422,8 @@ ref<DummyStore> adl_serializer<ref<DummyStore>>::from_json(const json & json)
     }();
     for (auto & [k, v] : getObject(valueAt(obj, "contents")))
         res->contents.insert({StorePath{k}, v});
+    for (auto & [k, v] : getObject(valueAt(obj, "derivations")))
+        res->derivations.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);
@@ -449,6 +451,15 @@ void adl_serializer<ref<DummyStore>>::to_json(json & json, const ref<DummyStore>
              });
              return obj;
          }()},
+        {"derivations",
+         [&] {
+             auto obj = json::object();
+             val->derivations.cvisit_all([&](const auto & kv) {
+                 auto & [k, v] = kv;
+                 obj[k.to_string()] = v;
+             });
+             return obj;
+         }()},
         {"build-trace",
          [&] {
              auto obj = json::object();