SERVER-41750 refactor renamed paths API.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/document_source_project_test.cpp b/src/mongo/db/pipeline/document_source_project_test.cpp
index ad0eecfe573..34b04a1ce2e 100644
--- a/src/mongo/db/pipeline/document_source_project_test.cpp
+++ b/src/mongo/db/pipeline/document_source_project_test.cpp
@@ -41,6 +41,7 @@
 #include "mongo/db/pipeline/document_source_mock.h"
 #include "mongo/db/pipeline/document_source_project.h"
 #include "mongo/db/pipeline/document_value_test_util.h"
+#include "mongo/db/pipeline/semantic_analysis.h"
 #include "mongo/db/pipeline/value.h"
 #include "mongo/unittest/unittest.h"
 
@@ -266,6 +267,29 @@ TEST_F(ProjectStageTest, CanUseRemoveSystemVariableToConditionallyExcludeProject
     ASSERT(project->getNext().isEOF());
 }
 
+TEST_F(ProjectStageTest, ProjectionCorrectlyReportsRenamesForwards) {
+    auto project = DocumentSourceProject::create(fromjson("{'renamedB' : '$b'}"), getExpCtx());
+    auto renames =
+        semantic_analysis::renamedPaths({"b"}, *project, semantic_analysis::Direction::kForward);
+    // renamedPaths should return a mapping of old name->new name for each path in interestingPaths
+    // if the paths are all unmodified (but possibly renamed). Because path b is preserved, but
+    // renamed (to renamedB) we expect a renamedPaths to return a mapping from b->renamedB.
+    auto single_rename = renames->extract("b");
+    ASSERT_FALSE(single_rename.empty());
+    ASSERT_EQUALS(single_rename.mapped(), "renamedB");
+    ASSERT_TRUE(renames->empty());
+}
+
+TEST_F(ProjectStageTest, ProjectionCorrectlyReportsRenamesBackwards) {
+    auto project = DocumentSourceProject::create(fromjson("{'renamedB' : '$b'}"), getExpCtx());
+    auto renames = semantic_analysis::renamedPaths(
+        {"renamedB"}, *project, semantic_analysis::Direction::kBackward);
+    auto single_rename = renames->extract("renamedB");
+    ASSERT_FALSE(single_rename.empty());
+    ASSERT_EQUALS(single_rename.mapped(), "b");
+    ASSERT_TRUE(renames->empty());
+}
+
 /**
  * Creates BSON for a DocumentSourceProject that represents projecting a new computed field nested
  * 'depth' levels deep.