Fix test flakiness for descriptor

test/MultiColumnJoinTest.cpp

@@ -2,6 +2,7 @@
 // Chair of Algorithms and Data Structures.
 // Author: Florian Kramer ([email protected])
 
+#include <absl/strings/str_split.h>
 #include <gtest/gtest.h>
 
 #include <array>
@@ -88,7 +89,22 @@ TEST(MultiColumnJoin, clone) {
   ASSERT_TRUE(clone);
   const auto& cloneReference = *clone;
   EXPECT_EQ(typeid(join), typeid(cloneReference));
-  EXPECT_EQ(cloneReference.getDescriptor(), join.getDescriptor());
+
+  std::string_view prefix = "MultiColumnJoin on ";
+  EXPECT_THAT(join.getDescriptor(), ::testing::StartsWith(prefix));
+  EXPECT_THAT(cloneReference.getDescriptor(), ::testing::StartsWith(prefix));
+  // Order of join columns is not deterministic.
+  auto getVars = [prefix](std::string_view string) {
+    string.remove_prefix(prefix.length());
+    std::vector<std::string> vars;
+    for (const auto& split : absl::StrSplit(string, ' ', absl::SkipEmpty())) {
+      vars.emplace_back(split);
+    }
+    ql::ranges::sort(vars);
+    return vars;
+  };
+  EXPECT_EQ(getVars(cloneReference.getDescriptor()),
+            getVars(join.getDescriptor()));
 
   EXPECT_NE(join.getChildren().at(0), cloneReference.getChildren().at(0));
   EXPECT_NE(join.getChildren().at(1), cloneReference.getChildren().at(1));