Improve test + comments

Author: alamb

datafusion/core/tests/parquet/mod.rs

@@ -108,11 +108,11 @@ struct ContextWithParquet {
 
 /// The output of running one of the test cases
 struct TestOutput {
-    /// The input string
+    /// The input query SQL
     sql: String,
     /// Execution metrics for the Parquet Scan
     parquet_metrics: MetricsSet,
-    /// number of rows in results
+    /// number of actual rows in results
     result_rows: usize,
     /// the contents of the input, as a string
     pretty_input: String,

datafusion/core/tests/parquet/row_group_pruning.rs

@@ -34,7 +34,7 @@ struct RowGroupPruningTest {
     expected_files_pruned_by_statistics: Option<usize>,
     expected_row_group_matched_by_bloom_filter: Option<usize>,
     expected_row_group_pruned_by_bloom_filter: Option<usize>,
-    expected_results: usize,
+    expected_rows: usize,
 }
 impl RowGroupPruningTest {
     // Start building the test configuration
@@ -48,7 +48,7 @@ impl RowGroupPruningTest {
             expected_files_pruned_by_statistics: None,
             expected_row_group_matched_by_bloom_filter: None,
             expected_row_group_pruned_by_bloom_filter: None,
-            expected_results: 0,
+            expected_rows: 0,
         }
     }
 
@@ -99,9 +99,9 @@ impl RowGroupPruningTest {
         self
     }
 
-    // Set the expected rows for the test
+    /// Set the number of expected rows from the output of this test
     fn with_expected_rows(mut self, rows: usize) -> Self {
-        self.expected_results = rows;
+        self.expected_rows = rows;
         self
     }
 
@@ -145,8 +145,10 @@ impl RowGroupPruningTest {
         );
         assert_eq!(
             output.result_rows,
-            self.expected_results,
-            "mismatched expected rows: {}",
+            self.expected_rows,
+            "Expected {} rows, got {}: {}",
+            output.result_rows,
+            self.expected_rows,
             output.description(),
         );
     }