Write a basic unit test for the dummy store

Tests the realisation functionality we just added.

Author: Ericson2314

src/libfetchers-tests/git.cc

@@ -183,7 +183,7 @@ TEST_F(GitTest, submodulePeriodSupport)
     auto store = [] {
         auto cfg = make_ref<DummyStoreConfig>(StoreReference::Params{});
         cfg->readOnly = false;
-        return cfg->openStore();
+        return cfg->openDummyStore();
     }();
 
     auto settings = fetchers::Settings{};

src/libstore-tests/dummy-store.cc

@@ -0,0 +1,36 @@
+#include <gtest/gtest.h>
+
+#include "nix/store/dummy-store.hh"
+#include "nix/store/globals.hh"
+#include "nix/store/realisation.hh"
+
+namespace nix {
+
+TEST(DummyStore, realisation_read)
+{
+    initLibStore(/*loadConfig=*/false);
+
+    auto store = [] {
+        auto cfg = make_ref<DummyStoreConfig>(StoreReference::Params{});
+        cfg->readOnly = false;
+        return cfg->openDummyStore();
+    }();
+
+    auto drvHash = Hash::parseExplicitFormatUnprefixed(
+        "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad", HashAlgorithm::SHA256, HashFormat::Base16);
+
+    auto outputName = "foo";
+
+    UnkeyedRealisation value{
+        .outPath = StorePath{"g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv"},
+    };
+
+    store->buildTrace.insert({drvHash, {{outputName, make_ref<UnkeyedRealisation>(value)}}});
+
+    auto value2 = store->queryRealisation({drvHash, outputName});
+
+    ASSERT_TRUE(value2);
+    EXPECT_EQ(*value2, value);
+}
+
+} // namespace nix

src/libstore-tests/meson.build

@@ -61,6 +61,7 @@ sources = files(
   'derivation.cc',
   'derived-path.cc',
   'downstream-placeholder.cc',
+  'dummy-store.cc',
   'http-binary-cache-store.cc',
   'legacy-ssh-store.cc',
   'local-binary-cache-store.cc',

src/libstore/dummy-store.cc

@@ -109,36 +109,10 @@ class WholeStoreViewAccessor : public SourceAccessor
 
 } // namespace
 
-struct DummyStore : virtual Store
+struct DummyStoreImpl : DummyStore
 {
     using Config = DummyStoreConfig;
 
-    ref<const Config> config;
-
-    struct PathInfoAndContents
-    {
-        UnkeyedValidPathInfo info;
-        ref<MemorySourceAccessor> contents;
-    };
-
-    /**
-     * This is map conceptually owns the file system objects for each
-     * store object.
-     */
-    boost::concurrent_flat_map<StorePath, PathInfoAndContents> contents;
-
-    /**
-     * The build trace maps the pair of a content-addressing (fixed or
-     * floating) derivations an one of its output to a
-     * (content-addressed) store object.
-     *
-     * It is [curried](https://en.wikipedia.org/wiki/Currying), so we
-     * instead having a single output with a `DrvOutput` key, we have an
-     * outer map for the derivation, and inner maps for the outputs of a
-     * given derivation.
-     */
-    boost::concurrent_flat_map<Hash, std::map<std::string, ref<UnkeyedRealisation>>> buildTrace;
-
     /**
      * This view conceptually just borrows the file systems objects of
      * each store object from `contents`, and combines them together
@@ -148,9 +122,9 @@ struct DummyStore : virtual Store
      */
     ref<WholeStoreViewAccessor> wholeStoreView = make_ref<WholeStoreViewAccessor>();
 
-    DummyStore(ref<const Config> config)
+    DummyStoreImpl(ref<const Config> config)
         : Store{*config}
-        , config(config)
+        , DummyStore{config}
     {
         wholeStoreView->setPathDisplay(config->storeDir);
     }
@@ -319,9 +293,9 @@ struct DummyStore : virtual Store
     }
 };
 
-ref<Store> DummyStore::Config::openStore() const
+ref<DummyStore> DummyStore::Config::openDummyStore() const
 {
-    return make_ref<DummyStore>(ref{shared_from_this()});
+    return make_ref<DummyStoreImpl>(ref{shared_from_this()});
 }
 
 static RegisterStoreImplementation<DummyStore::Config> regDummyStore;

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

@@ -3,8 +3,12 @@
 
 #include "nix/store/store-api.hh"
 
+#include <boost/unordered/concurrent_flat_map.hpp>
+
 namespace nix {
 
+struct DummyStore;
+
 struct DummyStoreConfig : public std::enable_shared_from_this<DummyStoreConfig>, virtual StoreConfig
 {
     DummyStoreConfig(const Params & params)
@@ -42,6 +46,11 @@ struct DummyStoreConfig : public std::enable_shared_from_this<DummyStoreConfig>,
         return {"dummy"};
     }
 
+    /**
+     * Same as `openStore`, just with a more precise return type.
+     */
+    ref<DummyStore> openDummyStore() const;
+
     ref<Store> openStore() const override;
 
     StoreReference getReference() const override
@@ -56,4 +65,51 @@ struct DummyStoreConfig : public std::enable_shared_from_this<DummyStoreConfig>,
     }
 };
 
+struct MemorySourceAccessor;
+
+/**
+ * Enough of the Dummy Store exposed for sake of writing unit tests
+ */
+struct DummyStore : virtual Store
+{
+    using Config = DummyStoreConfig;
+
+    ref<const Config> config;
+
+    struct PathInfoAndContents
+    {
+        UnkeyedValidPathInfo info;
+        ref<MemorySourceAccessor> contents;
+    };
+
+    /**
+     * This is map conceptually owns the file system objects for each
+     * store object.
+     */
+    boost::concurrent_flat_map<StorePath, PathInfoAndContents> contents;
+
+    /**
+     * The build trace maps the pair of a content-addressing (fixed or
+     * floating) derivations an one of its output to a
+     * (content-addressed) store object.
+     *
+     * It is [curried](https://en.wikipedia.org/wiki/Currying), so we
+     * instead having a single output with a `DrvOutput` key, we have an
+     * outer map for the derivation, and inner maps for the outputs of a
+     * given derivation.
+     */
+    boost::concurrent_flat_map<Hash, std::map<std::string, ref<UnkeyedRealisation>>> buildTrace;
+
+    DummyStore(ref<const Config> config)
+        : Store{*config}
+        , config(config)
+    {
+    }
+};
+
+ref<Store> DummyStoreConfig::openStore() const
+{
+    return openDummyStore();
+}
+
 } // namespace nix