fix: verify date with TDD

- add tests for the function

Signed-off-by: Ameya Shenoy <shenoy.ameya@gmail.com>

README.md

@@ -79,6 +79,12 @@ docker-compose exec backend python manage.py makemigrations
 docker-compose exec backend python manage.py migrate
 ```
 
+- To run unit tests
+
+```sh
+docker-compose exec backend python manage.py test
+```
+
 Similarly all django commands can be run this way.
 
 ## Endpoints

backend/app/tests.py

@@ -1,3 +1,40 @@
 from django.test import TestCase
+from unittest import mock
+from app.utils import verify_date
+import datetime
 
 # Create your tests here.
+class StubDate(datetime.datetime):
+    pass
+
+
+class TestApp(TestCase):
+    """Test app utils.
+
+    Publish time: datetime.datetime(2021, 2, 14, 12, 30)
+    """
+
+    @mock.patch('app.utils.datetime.datetime', StubDate)
+    def test_today_before_publish_time(self):
+        StubDate.now = classmethod(lambda cls: datetime.datetime(2021, 2, 12, 8, 0, 0))
+        date, _ = verify_date('2021-02-14', '')
+        self.assertEqual(date.date(), datetime.datetime(2021, 2, 11).date())
+
+    @mock.patch('app.utils.datetime.datetime', StubDate)
+    def test_today_after_publish_time(self):
+        StubDate.now = classmethod(lambda cls: datetime.datetime(2021, 2, 12, 13, 0, 0))
+        date, _ = verify_date('2021-02-14', '')
+        self.assertEqual(date.date(), datetime.datetime(2021, 2, 12).date())
+
+    @mock.patch('app.utils.datetime.datetime', StubDate)
+    def test_weekend_returns_friday(self):
+        StubDate.now = classmethod(lambda cls: datetime.datetime(2021, 2, 14, 13, 0, 0))
+        date, _ = verify_date('2021-02-14', '')
+        self.assertEqual(date.date(), datetime.datetime(2021, 2, 12).date())
+
+    @mock.patch('app.utils.datetime.datetime', StubDate)
+    def test_a_future_date(self):
+        StubDate.now = classmethod(lambda cls: datetime.datetime(2021, 2, 15, 13, 0, 0))
+        date, _ = verify_date('2021-02-20', '')
+        self.assertEqual(date.date(), datetime.datetime(2021, 2, 15).date())
+

backend/app/utils.py

@@ -8,6 +8,7 @@ import csv
 import json
 import datetime
 import logging
+from typing import Tuple
 
 from io import BytesIO, TextIOWrapper
 from zipfile import ZipFile
@@ -114,7 +115,10 @@ def populate_bhav_copy_data_into_postgres(data=None, date=None):
         del data[0]
     if date is None:
         date = datetime.datetime.now().date()
+    # data = stocks_csv_to_json(data)
     for stock in data:
+        # stock['date'] = date
+        # BhavCopyEquity.objects.get_or_create(**stock)
         BhavCopyEquity.objects.get_or_create(
             date=date,
             sc_code=int(stock[0]),
@@ -156,17 +160,36 @@ def stocks_csv_to_json(data):
     return stocks
 
 
-def verify_date(date, ret_message):
+def verify_date(date, ret_message) -> Tuple[datetime.datetime, str]:
+    """Verify current date.
+
+    Check current date and time and return the appropriate date. Also take care
+    of the following usecases
+    - if today before publish time return yesterdays data
+    - if today after publish time return todays data
+    - if a future date, return current day's data with time travel message
+    - if a weekend return Friday's data with custom message
+    """
     # Verify Date
     logger.info('Verifying date %s', date)
-    req_date = datetime.datetime.strptime(date, '%Y-%m-%d')
-    # 18:00 IST == 12:30 UTC
-    today = datetime.datetime.now().replace(hour=12, minute=30, second=0, microsecond=0)
-    logger.info('Req Date: %s; Today: %s', req_date, today)
-    if req_date > today:
+    curr_datetime = datetime.datetime.now() - datetime.timedelta(hours=5, minutes=30)
+    req_datetime = datetime.datetime.strptime(date, '%Y-%m-%d')
+    next_publish_time = curr_datetime.replace(hour=6, minute=0, second=0,
+                                              microsecond=0)
+    logger.info('Current IST Datetime: %s; Request Datetime: %s; Next Publish: %s',
+                curr_datetime, req_datetime, next_publish_time)
+    # Check for future date
+    if req_datetime.date() > curr_datetime.date():
         ret_message = "Time travel not yet invented! Returning latest available data."
-        req_date = today
-    if req_date.date() == today.date() and req_date < today:
-        req_date = today - datetime.timedelta(days=1)
-    return req_date, ret_message
+        req_datetime = curr_datetime
+    # Check for weekend
+    day_num = req_datetime.weekday()
+    if day_num in [5, 6]:
+        ret_message = "Markets are closed on weekends. Returning data for Friday."
+        req_datetime -= datetime.timedelta(days=day_num-4)  # change req to Friday
+    # Check for day
+    if req_datetime.date() == curr_datetime.date() and curr_datetime < next_publish_time:
+        ret_message = "Today's data not yet published, returning yesterday's data."
+        req_datetime -= datetime.timedelta(days=1)
+    return req_datetime, ret_message