starting CountryColumnsMergerTest

src/CountryColumnsMerger.py

@@ -0,0 +1,23 @@
+import pandas as pd
+
+
+class CountryColumnsMerger:
+
+    @staticmethod
+    def mergeCountryColumnOfSrcIntoDst(src: pd.DataFrame, dst: pd.DataFrame):
+        def merge(series):
+            if pd.isnull(series['COUNTRY_dst']):
+                return series['COUNTRY_src']
+            else:
+                return series['COUNTRY_dst']
+
+        merged = pd.merge(
+            dst,
+            src,
+            how = 'left',
+            left_index = True,
+            right_index = True,
+            suffixes=('_dst', '_src'))
+        merged['COUNTRY'] = merged.apply(merge, axis = 'columns').astype('string')
+        return merged.drop(columns = ['COUNTRY_dst', 'COUNTRY_src'])
+    

src/CountryColumnsMergerTest.py

@@ -0,0 +1,53 @@
+import unittest
+from TestHelper import TestHelper
+from pandas.testing import assert_frame_equal
+import pandas as pd
+from CountryColumnsMerger import CountryColumnsMerger
+
+
+class CountryColumnsMergerTest(unittest.TestCase):
+    
+    def test_mergeCountryColumns(self):
+        # Given
+        unknown = TestHelper.createDataFrame(
+                columns = ['COUNTRY'],
+                data = [  ['United Kingdom'],
+                          ['France'],
+                          [None]],
+                index = pd.Index(
+                        name = 'VAERS_ID',
+                        data = [
+                            '4711',
+                            '0815',
+                            '123']),
+                dtypes = {'COUNTRY': 'string'})
+        
+        known = TestHelper.createDataFrame(
+                columns = ['COUNTRY'],
+                data = [  ['United Kingdom'],
+                          ['Germany']],
+                index = pd.Index(
+                        name = 'VAERS_ID',
+                        data = [
+                            '4711',
+                            '123']),
+                dtypes = {'COUNTRY': 'string'})
+
+        # When
+        merged = CountryColumnsMerger.mergeCountryColumnOfSrcIntoDst(src = known, dst = unknown)
+
+        # Then
+        assert_frame_equal(
+            merged,
+            TestHelper.createDataFrame(
+                columns = ['COUNTRY'],
+                data = [  ['United Kingdom'],
+                          ['France'],
+                          ['Germany']],
+                index = pd.Index(
+                        name = 'VAERS_ID',
+                        data = [
+                            '4711',
+                            '0815',
+                            '123']),
+                dtypes = {'COUNTRY': 'string'}))