fix(3p/nix): Fix parseDrvPathWithOutputs r/1571

At some point the behavior of this function got changed as part of our
cleanup - this fixes it to behave the way the rest of the codebase
expects (and how it is documented in the header) and covers it with a
few tests.

Change-Id: Id4c91232968e73489cd866fb4a2a84bcf20d875e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1629
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>

2 files changed, 33 insertions, 3 deletions

diff --git a/third_party/nix/src/libstore/derivations.cc b/third_party/nix/src/libstore/derivations.cc
index 8a50f3c85b4d..978d39b94e7d 100644
--- a/third_party/nix/src/libstore/derivations.cc
+++ b/third_party/nix/src/libstore/derivations.cc
@@ -408,15 +408,15 @@ Hash hashDerivationModulo(Store& store, Derivation drv) {
   return hashString(htSHA256, drv.unparse());
 }
 
-// TODO(tazjin): doc comment?
 DrvPathWithOutputs parseDrvPathWithOutputs(absl::string_view path) {
   auto pos = path.find('!');
   if (pos == absl::string_view::npos) {
     return DrvPathWithOutputs(path, std::set<std::string>());
   }
 
-  return DrvPathWithOutputs(path.substr(pos + 1),
-                            absl::StrSplit(path, absl::ByChar(',')));
+  return DrvPathWithOutputs(
+      path.substr(0, pos),
+      absl::StrSplit(path.substr(pos + 1), absl::ByChar(',')));
 }
 
 Path makeDrvPathWithOutputs(const Path& drvPath,
diff --git a/third_party/nix/src/tests/derivations_test.cc b/third_party/nix/src/tests/derivations_test.cc
index e026fbe3b11c..1e2719addaf1 100644
--- a/third_party/nix/src/tests/derivations_test.cc
+++ b/third_party/nix/src/tests/derivations_test.cc
@@ -103,4 +103,34 @@ RC_GTEST_FIXTURE_PROP(DerivationsTest, UnparseParseRoundTrip,
   AssertDerivationsEqual(drv, parsed);
 }
 
+class ParseDrvPathWithOutputsTest : public DerivationsTest {};
+
+TEST(ParseDrvPathWithOutputsTest, ParseDrvPathWithOutputs) {
+  auto input = "/nix/store/my51f75kp056md84gq2v08pd140pcz57-test.drv!out";
+  auto result = nix::parseDrvPathWithOutputs(input);
+
+  ASSERT_EQ(result.first,
+            "/nix/store/my51f75kp056md84gq2v08pd140pcz57-test.drv");
+  ASSERT_EQ(result.second, nix::PathSet{"out"});
+}
+
+TEST(ParseDrvPathWithOutputsTest, ParseDrvPathWithMultipleOutputs) {
+  auto input = "/nix/store/my51f75kp056md84gq2v08pd140pcz57-test.drv!out,dev";
+  auto result = nix::parseDrvPathWithOutputs(input);
+
+  nix::PathSet expected = {"out", "dev"};
+
+  ASSERT_EQ(result.first,
+            "/nix/store/my51f75kp056md84gq2v08pd140pcz57-test.drv");
+  ASSERT_EQ(result.second, expected);
+}
+
+TEST(ParseDrvPathWithOutputsTest, ParseDrvPathWithNoOutputs) {
+  auto input = "/nix/store/my51f75kp056md84gq2v08pd140pcz57-test";
+  auto result = nix::parseDrvPathWithOutputs(input);
+
+  ASSERT_EQ(result.first, "/nix/store/my51f75kp056md84gq2v08pd140pcz57-test");
+  ASSERT_EQ(result.second, nix::PathSet());
+}
+
 }  // namespace nix