test(tvix): Cover scanForReferences in a test r/1627

Aded a few test cases covering the scanForReferences function, which had
been accidentally broken in 976a36c (which is now partially-reverted).
As part of this, since the test needed to generate hashes for store
paths, the logic in MakeStorePath to compress a sha256 hash down to 20
bytes and convert it to base32 has been extracted to a member function
on the Hash class.

Fixes: #34
Change-Id: Ie2d914688a80f42d0234d351a7cc0714fd15709e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1698
Tested-by: BuildkiteCI
Reviewed-by: kanepyork <rikingcoding@gmail.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/third_party/nix/src/tests/references_test.cc b/third_party/nix/src/tests/references_test.cc
new file mode 100644
index 000000000000..8dcb3ed37a8b
--- /dev/null
+++ b/third_party/nix/src/tests/references_test.cc
@@ -0,0 +1,74 @@
+#include "libstore/references.hh"
+
+#include <cstdio>
+#include <fstream>
+#include <ostream>
+#include <unordered_set>
+
+#include <absl/strings/str_format.h>
+#include <gtest/gtest.h>
+#include <rapidcheck.h>
+#include <rapidcheck/gtest.h>
+
+#include "libutil/hash.hh"
+
+class ReferencesTest : public ::testing::Test {};
+
+namespace nix {
+
+TEST(ReferencesTest, ScanForOneReferenceNotFound) {
+  char path[] = "store_XXXXXXX";
+  auto f = mkstemp(path);
+
+  auto hash = hashString(htSHA256, "foo");
+  auto ref = absl::StrFormat("/nix/store/%s-foo", hash.ToStorePathHash());
+
+  HashResult hr;
+  auto result = scanForReferences(path, {ref}, hr);
+
+  ASSERT_EQ(result.find(ref), result.end());
+
+  EXPECT_EQ(close(f), 0);
+}
+
+TEST(ReferencesTest, ScanForOneReferenceFound) {
+  char path[] = "store_XXXXXXX";
+  auto f = mkstemp(path);
+
+  auto hash = hashString(htSHA256, "foo");
+  auto ref = absl::StrFormat("/nix/store/%s-foo", hash.ToStorePathHash());
+
+  EXPECT_GT(write(f, ref.c_str(), sizeof(char) * ref.size()), 0);
+
+  HashResult hr;
+  auto result = scanForReferences(path, {ref}, hr);
+
+  ASSERT_NE(result.find(ref), result.end());
+
+  ASSERT_EQ(close(f), 0);
+}
+
+RC_GTEST_PROP(ReferencesTest, ScanForReferences,
+              (std::unordered_set<std::string> strs)) {
+  char path[] = "store_XXXXXXX";
+  auto f = mkstemp(path);
+
+  PathSet refs;
+  for (const auto& s : strs) {
+    auto hash = hashString(htSHA256, s);
+    auto ref = absl::StrFormat("/nix/store/%s-foo", hash.ToStorePathHash());
+    refs.insert(ref);
+    RC_ASSERT(write(f, ref.c_str(), sizeof(char) * ref.size()) > 0);
+  }
+
+  HashResult hr;
+  auto result = scanForReferences(path, refs, hr);
+
+  for (const auto& ref : refs) {
+    RC_ASSERT(result.find(ref) != result.end());
+  }
+
+  RC_ASSERT(close(f) == 0);
+}
+
+}  // namespace nix