[df] Check for empty file list in constructor

root-project · Nov 16, 2024 · bfa0b18 · bfa0b18
1 parent fce7be7
commit bfa0b18
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diff --git a/tree/dataframe/src/RLoopManager.cxx b/tree/dataframe/src/RLoopManager.cxx
@@ -1233,6 +1233,8 @@ std::shared_ptr<ROOT::Detail::RDF::RLoopManager>
 ROOT::Detail::RDF::CreateLMFromTTree(std::string_view datasetName, const std::vector<std::string> &fileNameGlobs,
                                      const std::vector<std::string> &defaultColumns, bool checkFile)
 {
+   if (fileNameGlobs.size() == 0)
+      throw std::invalid_argument("RDataFrame: empty list of input files.");
    // Introduce the same behaviour as in CreateLMFromFile for consistency.
    // Creating an RDataFrame with a non-existing file will throw early rather
    // than wait for the start of the graph execution.
@@ -1288,6 +1290,9 @@ ROOT::Detail::RDF::CreateLMFromFile(std::string_view datasetName, const std::vec
                                     const ROOT::RDF::ColumnNames_t &defaultColumns)
 {
 
+   if (fileNameGlobs.size() == 0)
+      throw std::invalid_argument("RDataFrame: empty list of input files.");
+
    auto inFile = OpenFileWithSanityChecks(fileNameGlobs[0]);
 
    if (inFile->Get<TTree>(datasetName.data())) {

diff --git a/tree/dataframe/test/dataframe_regression.cxx b/tree/dataframe/test/dataframe_regression.cxx
@@ -321,6 +321,16 @@ TEST_P(RDFRegressionTests, FileNameQueryNoExt)
    EXPECT_EQ(df.Count().GetValue(), 10);
 }
 
+TEST_P(RDFRegressionTests, EmptyFileList)
+{
+   try {
+      ROOT::RDataFrame df{"", {}};
+   } catch (const std::invalid_argument &e) {
+      const std::string expected{"RDataFrame: empty list of input files."};
+      EXPECT_EQ(e.what(), expected);
+   }
+}
+
 // run single-thread tests
 INSTANTIATE_TEST_SUITE_P(Seq, RDFRegressionTests, ::testing::Values(false));