[core] feat: add empty report

Author: AndreyMarkinPPC

libs/garf_core/garf_core/report.py

@@ -45,25 +45,25 @@ class GarfReport:
 
   def __init__(
     self,
-    results: Sequence[Sequence[parsers.ApiRowElement]],
-    column_names: Sequence[str],
+    results: Sequence[Sequence[parsers.ApiRowElement]] | None = None,
+    column_names: Sequence[str] | None = None,
     results_placeholder: Sequence[Sequence[parsers.ApiRowElement]]
     | None = None,
-    query_specification: query_editor.BaseQuerySpecification | None = None,
+    query_specification: query_editor.BaseQueryElements | None = None,
     auto_convert_to_scalars: bool = True,
   ) -> None:
     """Initializes GarfReport from API response.
 
     Args:
-        results: Contains data from Ads API in a form of nested list
-        column_names: Maps in each element in sublist of results to name.
-        results_placeholder: Optional placeholder values for missing results.
-        query_specification: Specification used to get data from Ads API.
-        auto_convert_to_scalars: Whether to simplify slicing operations.
+      results: Contains data from Ads API in a form of nested list
+      column_names: Maps in each element in sublist of results to name.
+      results_placeholder: Optional placeholder values for missing results.
+      query_specification: Specification used to get data from Ads API.
+      auto_convert_to_scalars: Whether to simplify slicing operations.
     """
-    self.results = results
-    self.column_names = column_names
-    self._multi_column_report = len(column_names) > 1
+    self.results = results or []
+    self.column_names = column_names or []
+    self._multi_column_report = len(column_names) > 1 if column_names else False
     if results_placeholder:
       self.results_placeholder = list(results_placeholder)
     else:
@@ -238,6 +238,8 @@ def get_value(
     Raises:
       GarfReportError: If row or column index are out of bounds.
     """
+    if not self:
+      raise GarfReportError('Cannot get value from an empty report')
     if column_index >= len(self.column_names):
       raise GarfReportError(
         'Column %d of report is not found; report contains only %d columns.',
@@ -298,6 +300,10 @@ def __getitem__(
     Raises:
         GarfReportError: When incorrect column_name specified.
     """
+    if not self:
+      if isinstance(key, (MutableSequence, str)):
+        raise GarfReportError(f"Cannot get '{key}' from an empty report")
+      raise GarfReportError('Cannot get element from an empty report')
     if isinstance(key, (MutableSequence, str)):
       return self._get_columns_slice(key)
     return self._get_rows_slice(key)
@@ -342,6 +348,8 @@ def _get_columns_slice(self, key: str | MutableSequence[str]) -> GarfReport:
     Raises:
         GarfReportError: When incorrect column_name specified.
     """
+    if not self:
+      return self
     if isinstance(key, str):
       key = [key]
     if set(key).issubset(set(self.column_names)):
@@ -356,15 +364,13 @@ def _get_columns_slice(self, key: str | MutableSequence[str]) -> GarfReport:
         results.append(rows)
       # TODO: propagate placeholders and query specification to new report
       return GarfReport(results, key)
-    non_existing_keys = set(key).intersection(set(self.column_names))
+    non_existing_keys = set(key).difference(set(self.column_names))
     if len(non_existing_keys) > 1:
-      message = (
-        f"Columns '{', '.join(list(non_existing_keys))}' "
-        'cannot be found in the report'
-      )
-    message = (
-      f"Column '{non_existing_keys.pop()}' " 'cannot be found in the report'
-    )
+      missing_columns = ', '.join(list(non_existing_keys))
+    else:
+      missing_columns = non_existing_keys.pop()
+
+    message = f"Columns '{missing_columns}' cannot be found in the report"
     raise GarfReportError(message)
 
   def __eq__(self, other) -> bool:

libs/garf_core/tests/unit/test_report.py

@@ -23,6 +23,11 @@
 from garf_core import report
 
 
+@pytest.fixture
+def empty_report():
+  return report.GarfReport()
+
+
 @pytest.fixture
 def single_element_report():
   return report.GarfReport(results=[[1]], column_names=['campaign_id'])
@@ -45,6 +50,9 @@ def multi_column_report():
 
 class TestGarfReport:
   class TestGarfReportIteration:
+    def test_empty_report_returns_empty_list(self, empty_report):
+      assert list(empty_report) == []
+
     def test_single_element_report_returns_garf_row(
       self, single_element_report
     ):
@@ -118,6 +126,9 @@ def test_hasattr_return_false_for_missing_value(self, multi_column_report):
       ]
 
   class TestGarfReportMisc:
+    def test_empty_report_length(self, empty_report):
+      assert len(empty_report) == 0
+
     def test_get_report_length(self, multi_column_report):
       assert len(multi_column_report) == len(multi_column_report.results)
 
@@ -126,7 +137,14 @@ def test_report_bool(self, single_element_report):
       single_element_report.results = []
       assert not single_element_report
 
+    def test_empty_report_bool_return_false(self, empty_report):
+      assert not empty_report
+
   class TestGarfReportAddition:
+    def test_add_two_empty_reports(self, empty_report):
+      added_report = empty_report + empty_report
+      assert len(added_report) == 0
+
     def test_add_two_reports(self, multi_column_report):
       added_report = multi_column_report + multi_column_report
       assert len(added_report) == len(multi_column_report.results) * 2
@@ -150,6 +168,15 @@ def test_add_reports_with_different_columns_raises_exception(
         multi_column_report + single_element_report
 
   class TestGarfReportSlicing:
+    def test_slicing_empty_garf_report_returns_empty_list(
+      self,
+      empty_report,
+    ):
+      with pytest.raises(
+        report.GarfReportError, match='Cannot get element from an empty report'
+      ):
+        empty_report[0:2]
+
     def test_slicing_multi_column_garf_report_returns_garf_report(
       self,
       multi_column_report,
@@ -177,6 +204,16 @@ def test_indexing_multi_column_garf_report_by_multi_index_returns_garf_report(
         results=[[1, 2], [2, 3]], column_names=['campaign_id', 'ad_group_id']
       )
 
+    def test_indexing_empty_garf_report_by_one_column_returns_garf_report(
+      self,
+      empty_report,
+    ):
+      with pytest.raises(
+        report.GarfReportError,
+        match="Cannot get 'campaign_id' from an empty report",
+      ):
+        empty_report['campaign_id']
+
     def test_indexing_multi_column_garf_report_by_one_column_returns_garf_report(
       self,
       multi_column_report,
@@ -193,11 +230,14 @@ def test_indexing_multi_column_garf_report_by_several_columns_returns_garf_repor
       new_report = multi_column_report[['campaign_id', 'ad_group_id']]
       assert new_report == multi_column_report
 
-    def test_indexing_multi_column_garf_report_by_non_existing_column_raises_exception(
+    def test_indexing_multi_column_garf_report_by_non_existing_column_raises_garf_report_error(
       self,
       multi_column_report,
     ):
-      with pytest.raises(report.GarfReportError):
+      with pytest.raises(
+        report.GarfReportError,
+        match="Columns 'ad_group' cannot be found in the report",
+      ):
         multi_column_report[['campaign_id', 'ad_group']]
 
     def test_slicing_single_column_garf_report_returns_report(
@@ -551,18 +591,39 @@ def test_from_json_with_non_dict_elements_in_list_raises_type_error(self):
       ):
         report.GarfReport.from_json(json_str)
 
+    def test_convert_empty_report_to_pandas_returns_empty_dataframe(
+      self, empty_report
+    ):
+      expected = pd.DataFrame()
+      assert empty_report.to_pandas().equals(expected)
+
     def test_convert_report_to_pandas(self, multi_column_report):
       expected = pd.DataFrame(
         data=[[1, 2], [2, 3], [3, 4]], columns=['campaign_id', 'ad_group_id']
       )
       assert multi_column_report.to_pandas().equals(expected)
 
+    def test_convert_empty_report_to_polars_returns_empty_dataframe(
+      self, empty_report
+    ):
+      expected = pl.DataFrame()
+      assert empty_report.to_polars().equals(expected)
+
     def test_convert_report_to_polars(self, multi_column_report):
       expected = pl.DataFrame(
         data=[[1, 2], [2, 3], [3, 4]], schema=['campaign_id', 'ad_group_id']
       )
       assert multi_column_report.to_polars().equals(expected)
 
+    def test_get_value_empty_report_raises_garf_report_error(
+      self,
+      empty_report,
+    ):
+      with pytest.raises(
+        report.GarfReportError, match='Cannot get value from an empty report'
+      ):
+        empty_report.get_value()
+
     def test_get_value_single_element_report_returns_correct_value(
       self,
       single_element_report,
@@ -593,6 +654,9 @@ def test_get_value_raises_exception_when_row_index_out_of_bound(
         single_element_report.get_value(row_index=1)
 
   class TestGarfReportEquality:
+    def test_empty_reports_are_equal(self):
+      assert report.GarfReport() == report.GarfReport()
+
     def test_report_with_different_columns_not_equal(
       self, single_element_report, multi_column_report
     ):