refactor: simplify some strange string formatting

Author: nedbat

tests/test_data.py

@@ -584,7 +584,7 @@ def test_read_write_arcs(self):
         assert_arcs3_data(covdata2)
 
     def test_read_errors(self):
-        msg = r"Couldn't .* '.*[/\\]{0}': \S+"
+        msg = r"Couldn't .* '.*[/\\]{}': \S+"
 
         self.make_file("xyzzy.dat", "xyzzy")
         with pytest.raises(CoverageException, match=msg.format("xyzzy.dat")):
@@ -602,15 +602,15 @@ def test_read_sql_errors(self):
         with sqlite3.connect("wrong_schema.db") as con:
             con.execute("create table coverage_schema (version integer)")
             con.execute("insert into coverage_schema (version) values (99)")
-        msg = r"Couldn't .* '.*[/\\]{}': wrong schema: 99 instead of \d+".format("wrong_schema.db")
+        msg = r"Couldn't .* '.*[/\\]wrong_schema.db': wrong schema: 99 instead of \d+"
         with pytest.raises(CoverageException, match=msg):
             covdata = DebugCoverageData("wrong_schema.db")
             covdata.read()
         assert not covdata
 
         with sqlite3.connect("no_schema.db") as con:
             con.execute("create table foobar (baz text)")
-        msg = r"Couldn't .* '.*[/\\]{}': \S+".format("no_schema.db")
+        msg = r"Couldn't .* '.*[/\\]no_schema.db': \S+"
         with pytest.raises(CoverageException, match=msg):
             covdata = DebugCoverageData("no_schema.db")
             covdata.read()

tests/test_process.py

@@ -1654,9 +1654,9 @@ def run_in_venv(cmd):
     """
     words = cmd.split()
     if env.WINDOWS:
-        words[0] = r"{}\Scripts\{}.exe".format("venv", words[0])
+        words[0] = fr"venv\Scripts\{words[0]}.exe"
     else:
-        words[0] = "{}/bin/{}".format("venv", words[0])
+        words[0] = fr"venv/bin/{words[0]}"
     status, output = run_command(" ".join(words))
     assert status == 0
     return output