[LNT] Python 3 support: Parse HTML as text

[thopre]

Summary

Several tests and the testsuite run import code parse text read from the
data attribute of a Flask response object (werkzeug.wrappers.Response).
However, in Python3 reading from that attribute yields binary data.
The attribute is in fact a property whose getter get_data() as a as_text
parameter that allows to request the result to be a string instead.

This commit adapts all reads from that property to request strings
instead of binary data (the default), except for a few cases in
tests/server/ui/V4Pages.py where the data is fed to ElementTree's
fromstring method in get_xml_tree() which tries to reencode it in ascii
in Python 2 mode if it gets a unicode string.

[thopre]

Merge more similar cases into this patch

[PrzemekWirkus]

LGTM but someone else must approve.

tests/server/ui/test_api_modify.py

68 ↗

(On Diff #224986)

Nitpick:

We indeed tend toward assertEqual for Python 3.
You've already replaced one assertEquala with assertEqual in this patch, could you clean this one up as well?

[thopre]

tests/server/ui/test_api_modify.py

68 ↗

(On Diff #224986)

I've made a separate diff fixing all existing use of assertEquals: https://reviews.llvm.org/D71057

[thopre]

Committed as b2e114bd7f7c2d6fe08edbe0c5811768e703727d

tests/server/db/Migrations.py

def sanity_check_instance(instance_path):
     # Create a test client.
     client = app.test_client()
 
     # Fetch the index page.
     index = client.get('/')
 
     # Visit all the test suites.
     test_suite_link_rex = re.compile("""  <a href="(.*)">(.*)</a><br>""")
-    test_suite_list_start = index.data.index("<h3>Test Suites</h3>")
-    test_suite_list_end = index.data.index("</div>", test_suite_list_start)
-    for ln in index.data[test_suite_list_start:test_suite_list_end].split("\n"):
+    data = index.get_data(as_text=True)
+    test_suite_list_start = data.index("<h3>Test Suites</h3>")
+    test_suite_list_end = data.index("</div>", test_suite_list_start)
+    for ln in data[test_suite_list_start:test_suite_list_end].split("\n"):
         # Ignore non-matching lines.
         print(ln, file=sys.stderr)
         m = test_suite_link_rex.match(ln)
         if not m:
             continue
 
         # We found a test suite link...
         link,name = m.groups()