feat: add CalculateEnterpriseDiscountedPrice pipeline step for course mode checkout

[pwnage101]

https://2u-internal.atlassian.net/browse/ENT-11573

openedx-filters #338 — CourseModePriceRequested filter definition
edx-enterprise #2556 — CalculateEnterpriseDiscountedPrice pipeline step
edx-platform #365 — view wired to invoke the filter

Prerequisites: local devstack running with all three branches installed (Runbook); an enterprise customer, an enterprise learner, and a course with a verified mode that has a non-empty SKU and a future expiration date.

E2E Testing Instructions:

Note: replace any enterprise customer uuids, users, or course keys with your own applicable local data.

In lms/envs/devstack.py, confirm/add, then restart after to capture changes:

AUTOMATIC_AUTH_FOR_TESTING = True
RESTRICT_AUTOMATIC_AUTH = False

Test 1: Check if pipeline correctly hooked up, and then check against control user with no enterprise link
Write the test file in lms-shell

cat > /tmp/test1.py << 'EOF'
from django.test import Client

client = Client()
response = client.get(
    '/auto_auth',
    {'username': 'e2e_control_user', 'password': 'testpass123'},
    follow=True,
)
print("auto_auth status:", response.status_code)

course_id = "course-v1:edX+DemoX+Demo_Course"
response = client.get(f"/course_modes/choose/{course_id}/", follow=True)
print("choose status:", response.status_code)
content = response.content.decode()
print("contains '149':", "149" in content)
EOF

Then execute the file in the bash script exec(open('/tmp/test1.py').read())

Expected: choose status: 200, contains '149': True.

Test 2: Check against enterprise-linked user with SKU present on course

cat > /tmp/test2.py << 'EOF'
from django.test import Client

client = Client()
client.get('/auto_auth', {'username': 'e2e_enterprise_user', 'password': 'testpass123'}, follow=True)

enterprise_uuid = "8400978a-7eb5-43a8-8a02-aa6063e842e2"
course_id = "course-v1:edX+DemoX+Demo_Course"

# The 'new_enterprise_login=yes' param bypasses RouterView's force_fresh_session
# check, which otherwise logs out any session not flagged as freshly SSO'd
r1 = client.get(
    f"/enterprise/{enterprise_uuid}/course/{course_id}/enroll/",
    {"new_enterprise_login": "yes"},
    follow=True,
)
print("landing hit status:", r1.status_code)

r2 = client.get(f"/course_modes/choose/{course_id}/", follow=True)
print("choose status:", r2.status_code)
content = r2.content.decode()
print("contains '149':", "149" in content)
EOF

Expected: no /logout in the log, choose status: 200, log line [e-commerce calculate endpoint] The discounted price for sku [8CF08E5]... is [149.0] confirming the ecommerce call happened and returned the (undiscounted) price.

Test 3: Check against enterprise-linked user, verified mode with no SKU

Create a no-SKU verified mode on a second course — inside make lms-shell, at >>>:

from common.djangoapps.course_modes.models import CourseMode

CourseMode.objects.create(
    course_id="course-v1:edX+E202+3T2025",
    mode_slug="verified",
    mode_display_name="Verified Certificate",
    min_price=100,
    currency="usd",
    sku="",
)

cat > /tmp/test3.py << 'EOF'
from django.test import Client

client = Client()
client.get('/auto_auth', {'username': 'e2e_enterprise_user', 'password': 'testpass123'}, follow=True)

enterprise_uuid = "8400978a-7eb5-43a8-8a02-aa6063e842e2"
course_id = "course-v1:edX+E202+3T2025"

# This course isn't seeded in the discovery service, so the landing page 500s
# on a pre-existing edx-enterprise bug (discovery.py:251) — but the enterprise
# customer is written to session before that crash, so we catch it and proceed
try:
    r1 = client.get(
        f"/enterprise/{enterprise_uuid}/course/{course_id}/enroll/",
        {"new_enterprise_login": "yes"},
        follow=True,
    )
    print("landing hit status:", r1.status_code)
except Exception as e:
    print("landing hit raised (expected, discovery API 404):", type(e).__name__)

r2 = client.get(f"/course_modes/choose/{course_id}/", follow=True)
print("choose status:", r2.status_code)
content = r2.content.decode()
print("contains '100':", "100" in content)
EOF

Expected: choose status: 200, contains '100': True, and — the key check — no [e-commerce calculate endpoint] log line, confirming the SKU guard blocked the ecommerce call entirely.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.72%. Comparing base (2f9c450) to head (d234402).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2556      +/-   ##
==========================================
+ Coverage   86.70%   86.72%   +0.01%     
==========================================
  Files         259      260       +1     
  Lines       17017    17041      +24     
  Branches     1681     1683       +2     
==========================================
+ Hits        14754    14778      +24     
  Misses       1927     1927              
  Partials      336      336              

Flag	Coverage Δ
unittests	86.72% <100.00%> (+0.01%)	⬆️

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[pwnage101]

❌ per edx/edx-platform#365 (comment)

[pwnage101]

✅ LGTM!