Add test_to_csv()

release_notes.md

@@ -605,4 +605,5 @@ Benchmark.
 
 Other converters also have some not big speed improvements.
 
-9. [TH2-5213] Extend cache_files_reading_speed with csv support.
+9. [TH2-5213] Extend cache_files_reading_speed with csv support. Added `Data.to_json` method, that converts 
+data to valid csv.

tests/test_files/file_to_test_to_csv.csv

@@ -0,0 +1,3 @@
+a,b,c,d
+1,2,,
+,,3,4

tests/test_files/file_to_test_to_csv_expected.csv

@@ -0,0 +1,3 @@
+a,b,c,d
+1,2,,
+,,3,4

tests/tests_unit/test_data/test_data.py

@@ -310,6 +310,18 @@ def test_to_json():
             assert l1 == l2
 
 
+def test_to_csv():
+    data = Data([{"a": 1, "b": 2}, {"c": 3, "d": 4}])
+    path_result = "tests/test_files/file_to_test_to_csv.csv"
+    path_expected = "tests/test_files/file_to_test_to_csv_expected.csv"
+
+    data.to_csv(path_result, overwrite=True)
+
+    with open(path_result, encoding="utf-8") as f1, open(path_expected, encoding="utf-8") as f2:
+        for l1, l2 in zip(f1, f2):
+            assert l1 == l2
+
+
 class TestDataObjectJoining:
     @classmethod
     def setup_class(cls):

th2_data_services/data.py

@@ -1146,7 +1146,7 @@ def to_csv(
         """Converts Data to csv.
 
         Args:
-            filename (str): Output JSON filename.
+            filename (str): Output CSV filename.
             overwrite (bool, optional): Overwrite if filename exists. Defaults to False.
 
         NOTE:
@@ -1173,7 +1173,7 @@ def to_csv(
                 writer.writerows(self)
             else:
                 writer = csv.DictWriter(
-                    file, fieldnames=list(set().union(*[d.keys() for d in self]))
+                    file, fieldnames=sorted(set().union(*[d.keys() for d in self]))
                 )
                 writer.writeheader()
                 for row_dict in self: