Added another test to show couple of ways we can get values from XML response using Xpath

Author: Gaurav Singh

config.py

@@ -1,2 +1,2 @@
 BASE_URI = 'http://0.0.0.0:5000/api/people'
-COVID_TRACKER_HOST = 'http://127.0.0.1:5000'
+COVID_TRACKER_HOST = 'http://127.0.0.1:3000'

tests/covid_test.py

@@ -11,7 +11,27 @@ def test_covid_cases_have_crossed_a_million():
     pretty_print(response.headers)
 
     response_xml = response.text
-    tree = etree.fromstring(bytes(response_xml, encoding='utf8'))
-    total_cases = tree.xpath("//data/summary/total_cases")[0].text
+    xml_tree = etree.fromstring(bytes(response_xml, encoding='utf8'))
 
+    # use .xpath on xml_tree object to evaluate the expression
+    total_cases = xml_tree.xpath("//data/summary/total_cases")[0].text
     assert_that(int(total_cases)).is_greater_than(1000000)
+
+
+def test_overall_covid_cases_match_sum_of_total_cases_by_country():
+    response = requests.get(f'{COVID_TRACKER_HOST}/api/v1/summary/latest')
+    pretty_print(response.headers)
+
+    response_xml = response.text
+    xml_tree = etree.fromstring(bytes(response_xml, encoding='utf8'))
+
+    overall_cases = int(xml_tree.xpath("//data/summary/total_cases")[0].text)
+    # Another way to specify XPath first and then use to evaluate
+    # on an XML tree
+    search_for = etree.XPath("//data//regions//total_cases")
+    cases_by_country = 0
+    for region in search_for(xml_tree):
+        cases_by_country += int(region.text)
+
+    assert_that(overall_cases).is_greater_than(cases_by_country)
+