More property tests

Also put proper comparison methods on `DerivedPath` and
`NixStringContextElem`, which is needed for the tests but good in
general.

src/libstore/tests/derived-path.cc

@@ -0,0 +1,52 @@
+#include <regex>
+
+#include <nlohmann/json.hpp>
+#include <gtest/gtest.h>
+#include <rapidcheck/gtest.h>
+
+#include "tests/derived-path.hh"
+#include "tests/libstore.hh"
+
+namespace rc {
+using namespace nix;
+
+Gen<DerivedPath> Arbitrary<DerivedPath>::arbitrary()
+{
+    switch (*gen::inRange<uint8_t>(0, 1)) {
+    case 0:
+        return gen::just((DerivedPath) DerivedPath::Opaque {
+            .path = *gen::arbitrary<StorePath>(),
+        });
+    default:
+        return gen::just((DerivedPath) DerivedPath::Built {
+            .drvPath = *gen::arbitrary<StorePath>(),
+            .outputs = *gen::arbitrary<OutputsSpec>(),
+        });
+    }
+}
+
+}
+
+namespace nix {
+
+class DerivedPathTest : public LibStoreTest
+{
+};
+
+// FIXME: `RC_GTEST_FIXTURE_PROP` isn't calling `SetUpTestSuite` because it is
+// no a real fixture.
+//
+// See https://github.com/emil-e/rapidcheck/blob/master/doc/gtest.md#rc_gtest_fixture_propfixture-name-args
+TEST_F(DerivedPathTest, force_init)
+{
+}
+
+RC_GTEST_FIXTURE_PROP(
+    DerivedPathTest,
+    prop_round_rip,
+    (const DerivedPath & o))
+{
+    RC_ASSERT(o == DerivedPath::parse(*store, o.to_string(*store)));
+}
+
+}

src/libstore/tests/derived-path.hh

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <rapidcheck/gen/Arbitrary.h>
+
+#include <derived-path.hh>
+
+#include "tests/path.hh"
+#include "tests/outputs-spec.hh"
+
+namespace rc {
+using namespace nix;
+
+template<>
+struct Arbitrary<DerivedPath> {
+    static Gen<DerivedPath> arbitrary();
+};
+
+}

src/libstore/tests/local.mk

@@ -24,6 +24,6 @@ libstore-tests_SOURCES := $(wildcard $(d)/*.cc)
 
 libstore-tests_CXXFLAGS += -I src/libstore -I src/libutil
 
-libstore-tests_LIBS = libstore libutil
+libstore-tests_LIBS = libutil-tests libstore libutil
 
 libstore-tests_LDFLAGS := -lrapidcheck $(GTEST_LIBS)

src/libstore/tests/outputs-spec.cc

@@ -2,6 +2,7 @@
 
 #include <nlohmann/json.hpp>
 #include <gtest/gtest.h>
+#include <rapidcheck/gtest.h>
 
 namespace nix {
 
@@ -199,3 +200,34 @@ TEST_JSON(ExtendedOutputsSpec, names, R"(["a","b"])", (ExtendedOutputsSpec::Expl
 #undef TEST_JSON
 
 }
+
+namespace rc {
+using namespace nix;
+
+Gen<OutputsSpec> Arbitrary<OutputsSpec>::arbitrary()
+{
+    switch (*gen::inRange<uint8_t>(0, 1)) {
+    case 0:
+        return gen::just((OutputsSpec) OutputsSpec::All { });
+    default:
+        return gen::just((OutputsSpec) OutputsSpec::Names {
+            *gen::nonEmpty(gen::container<StringSet>(gen::map(
+                gen::arbitrary<StorePathName>(),
+                [](StorePathName n) { return n.name; }))),
+        });
+    }
+}
+
+}
+
+namespace nix {
+
+RC_GTEST_PROP(
+    OutputsSpec,
+    prop_round_rip,
+    (const OutputsSpec & o))
+{
+    RC_ASSERT(o == OutputsSpec::parse(o.to_string()));
+}
+
+}

src/libstore/tests/outputs-spec.hh

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <rapidcheck/gen/Arbitrary.h>
+
+#include <outputs-spec.hh>
+
+#include <tests/path.hh>
+
+namespace rc {
+using namespace nix;
+
+template<>
+struct Arbitrary<OutputsSpec> {
+    static Gen<OutputsSpec> arbitrary();
+};
+
+}

src/libstore/tests/path.cc

@@ -7,6 +7,7 @@
 #include "path-regex.hh"
 #include "store-api.hh"
 
+#include "tests/hash.hh"
 #include "tests/libstore.hh"
 #include "tests/path.hh"
 
@@ -74,12 +75,14 @@ void showValue(const StorePath & p, std::ostream & os) {
 namespace rc {
 using namespace nix;
 
-Gen<StorePath> Arbitrary<StorePath>::arbitrary()
+Gen<StorePathName> Arbitrary<StorePathName>::arbitrary()
 {
-    auto len = *gen::inRange<size_t>(1, StorePath::MaxPathLen);
+    auto len = *gen::inRange<size_t>(
+        1,
+        StorePath::MaxPathLen - std::string_view { HASH_PART }.size());
 
-    std::string pre { HASH_PART "-" };
-    pre.reserve(pre.size() + len);
+    std::string pre;
+    pre.reserve(len);
 
     for (size_t c = 0; c < len; ++c) {
         switch (auto i = *gen::inRange<uint8_t>(0, 10 + 2 * 26 + 6)) {
@@ -114,7 +117,17 @@ Gen<StorePath> Arbitrary<StorePath>::arbitrary()
         }
     }
 
-    return gen::just(StorePath { pre });
+    return gen::just(StorePathName {
+        .name = std::move(pre),
+    });
+}
+
+Gen<StorePath> Arbitrary<StorePath>::arbitrary()
+{
+    return gen::just(StorePath {
+        *gen::arbitrary<Hash>(),
+        (*gen::arbitrary<StorePathName>()).name,
+    });
 }
 
 } // namespace rc

src/libstore/tests/path.hh

@@ -1,12 +1,25 @@
 #pragma once
 
-#include <rapidcheck.h>
+#include <rapidcheck/gen/Arbitrary.h>
 
-#include "path.hh"
+#include <path.hh>
+
+namespace nix {
+
+struct StorePathName {
+    std::string name;
+};
+
+}
 
 namespace rc {
 using namespace nix;
 
+template<>
+struct Arbitrary<StorePathName> {
+    static Gen<StorePathName> arbitrary();
+};
+
 template<>
 struct Arbitrary<StorePath> {
     static Gen<StorePath> arbitrary();