cleanup: Update codebase to expect Python 3.6

- Bump minimum version to Python 3.6.
- Use f-strings in a lot of places.

Change-Id: I2aa70197230fcec2eff8e7c8eb754f20c08075bb
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/389034
Tested-by: Jason R. Coombs <jaraco@google.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Commit-Queue: Jason R. Coombs <jaraco@google.com>

tests/test_git_command.py

@@ -19,12 +19,7 @@ import os
 import re
 import subprocess
 import unittest
-
-
-try:
-    from unittest import mock
-except ImportError:
-    import mock
+from unittest import mock
 
 import git_command
 import wrapper

tests/test_git_config.py

@@ -100,7 +100,7 @@ class GitConfigReadOnlyTests(unittest.TestCase):
             ("intg", 10737418240),
         )
         for key, value in TESTS:
-            self.assertEqual(value, self.config.GetInt("section.%s" % (key,)))
+            self.assertEqual(value, self.config.GetInt(f"section.{key}"))
 
 
 class GitConfigReadWriteTests(unittest.TestCase):

tests/test_git_superproject.py

@@ -34,7 +34,7 @@ class SuperprojectTestCase(unittest.TestCase):
     PARENT_SID_KEY = "GIT_TRACE2_PARENT_SID"
     PARENT_SID_VALUE = "parent_sid"
     SELF_SID_REGEX = r"repo-\d+T\d+Z-.*"
-    FULL_SID_REGEX = r"^%s/%s" % (PARENT_SID_VALUE, SELF_SID_REGEX)
+    FULL_SID_REGEX = rf"^{PARENT_SID_VALUE}/{SELF_SID_REGEX}"
 
     def setUp(self):
         """Set up superproject every time."""

tests/test_git_trace2_event_log.py

@@ -61,7 +61,7 @@ class EventLogTestCase(unittest.TestCase):
     PARENT_SID_KEY = "GIT_TRACE2_PARENT_SID"
     PARENT_SID_VALUE = "parent_sid"
     SELF_SID_REGEX = r"repo-\d+T\d+Z-.*"
-    FULL_SID_REGEX = r"^%s/%s" % (PARENT_SID_VALUE, SELF_SID_REGEX)
+    FULL_SID_REGEX = rf"^{PARENT_SID_VALUE}/{SELF_SID_REGEX}"
 
     def setUp(self):
         """Load the event_log module every time."""

tests/test_manifest_xml.py

@@ -198,13 +198,13 @@ class ValueTests(unittest.TestCase):
     def test_bool_true(self):
         """Check XmlBool true values."""
         for value in ("yes", "true", "1"):
-            node = self._get_node('<node a="%s"/>' % (value,))
+            node = self._get_node(f'<node a="{value}"/>')
             self.assertTrue(manifest_xml.XmlBool(node, "a"))
 
     def test_bool_false(self):
         """Check XmlBool false values."""
         for value in ("no", "false", "0"):
-            node = self._get_node('<node a="%s"/>' % (value,))
+            node = self._get_node(f'<node a="{value}"/>')
             self.assertFalse(manifest_xml.XmlBool(node, "a"))
 
     def test_int_default(self):
@@ -220,7 +220,7 @@ class ValueTests(unittest.TestCase):
     def test_int_good(self):
         """Check XmlInt numeric handling."""
         for value in (-1, 0, 1, 50000):
-            node = self._get_node('<node a="%s"/>' % (value,))
+            node = self._get_node(f'<node a="{value}"/>')
             self.assertEqual(value, manifest_xml.XmlInt(node, "a"))
 
     def test_int_invalid(self):

tests/test_project.py

@@ -151,7 +151,7 @@ class CopyLinkTestCase(unittest.TestCase):
                     # "".
                     break
                 result = os.path.exists(path)
-                msg.append("\tos.path.exists(%s): %s" % (path, result))
+                msg.append(f"\tos.path.exists({path}): {result}")
                 if result:
                     msg.append("\tcontents: %r" % os.listdir(path))
                     break