[task] handle edge case of template missing the test description head…

…er and with description header as last item

tasks/github_tasks.py

@@ -487,9 +487,11 @@ def extract_test_qa_description(pr_body: str) -> str:
         if line.startswith('### Describe how to test'):
             index_of_test_qa_section = i
             break
-    index_of_next_section = -1
+    if index_of_test_qa_section == -1:
+        return ''
+    index_of_next_section = len(pr_body_lines)
     for i in range(index_of_test_qa_section + 1, len(pr_body_lines)):
-        if pr_body_lines[i].startswith('### Possible Drawbacks'):
+        if pr_body_lines[i].startswith('### '):
             index_of_next_section = i
             break
     if index_of_next_section == -1:

tasks/unit_tests/github_tasks_tests.py

@@ -230,6 +230,29 @@ class TestExtractBodyCase:
 """,
                 expected="Here is a test description with special characters: `~!@#$,%^&*()_-+={[]}|\\:;\"'<>.?/",
             ),
+            TestExtractBodyCase(
+                name="Missing test description header",
+                body="""### What does this PR do?
+
+### Motivation
+
+### Possible Drawbacks / Trade-offs
+
+### Additional Notes
+""",
+                expected="",
+            ),
+            TestExtractBodyCase(
+                name="Missing next section header",
+                body="""### What does this PR do?
+
+### Motivation
+
+### Describe how to test/QA your changes
+Here is how to test this PR
+""",
+                expected="Here is how to test this PR",
+            ),
         ]
 
         for tc in testcases: