refactor: convert more %-formatting to f-strings

5 files changed, 26 insertions, 21 deletions

diff --git a/coverage/cmdline.py b/coverage/cmdline.py
index cc7d8082..d1e8f283 100644
--- a/coverage/cmdline.py
+++ b/coverage/cmdline.py
@@ -46,8 +46,8 @@ class Opts:
         choices=CONCURRENCY_CHOICES,
         help=(
             "Properly measure code using a concurrency library. "
-            "Valid values are: %s."
-        ) % ", ".join(CONCURRENCY_CHOICES),
+            "Valid values are: {}."
+        ).format(", ".join(CONCURRENCY_CHOICES)),
     )
     context = optparse.make_option(
         '', '--context', action='store', metavar="LABEL",
@@ -299,7 +299,7 @@ class CmdOptionParser(CoverageOptionParser):
     def __eq__(self, other):
         # A convenience equality, so that I can put strings in unit test
         # results, and they will compare equal to objects.
-        return (other == "<CmdOptionParser:%s>" % self.cmd)
+        return (other == f"<CmdOptionParser:{self.cmd}>")
 
     __hash__ = None     # This object doesn't need to be hashed.
 
@@ -506,7 +506,7 @@ def show_help(error=None, topic=None, parser=None):
         if help_msg:
             print(help_msg.format(**help_params))
         else:
-            print("Don't know topic %r" % topic)
+            print(f"Don't know topic {topic!r}")
     print("Full documentation is at {__url__}".format(**help_params))
 
 
@@ -541,7 +541,7 @@ class CoverageScript:
         else:
             parser = CMDS.get(argv[0])
             if not parser:
-                show_help("Unknown command: '%s'" % argv[0])
+                show_help(f"Unknown command: {argv[0]!r}")
                 return ERR
             argv = argv[1:]
 
@@ -765,22 +765,22 @@ class CoverageScript:
                 sys_info = self.coverage.sys_info()
                 print(info_header("sys"))
                 for line in info_formatter(sys_info):
-                    print(" %s" % line)
+                    print(f" {line}")
             elif info == 'data':
                 self.coverage.load()
                 data = self.coverage.get_data()
                 print(info_header("data"))
-                print("path: %s" % data.data_filename())
+                print(f"path: {data.data_filename()}")
                 if data:
-                    print("has_arcs: %r" % data.has_arcs())
+                    print(f"has_arcs: {data.has_arcs()!r}")
                     summary = line_counts(data, fullpath=True)
                     filenames = sorted(summary.keys())
-                    print("\n%d files:" % len(filenames))
+                    print(f"\n{len(filenames)} files:")
                     for f in filenames:
-                        line = "%s: %d lines" % (f, summary[f])
+                        line = f"{f}: {summary[f]} lines"
                         plugin = data.file_tracer(f)
                         if plugin:
-                            line += " [%s]" % plugin
+                            line += f" [{plugin}]"
                         print(line)
                 else:
                     print("No data collected")
@@ -788,12 +788,12 @@ class CoverageScript:
                 print(info_header("config"))
                 config_info = self.coverage.config.__dict__.items()
                 for line in info_formatter(config_info):
-                    print(" %s" % line)
+                    print(f" {line}")
             elif info == "premain":
                 print(info_header("premain"))
                 print(short_stack())
             else:
-                show_help("Don't know what you mean by %r" % info)
+                show_help(f"Don't know what you mean by {info!r}")
                 return ERR
 
         return OK
diff --git a/coverage/collector.py b/coverage/collector.py
index e219c928..f9e9d14f 100644
--- a/coverage/collector.py
+++ b/coverage/collector.py
@@ -116,7 +116,7 @@ class Collector:
         # We can handle a few concurrency options here, but only one at a time.
         these_concurrencies = self.SUPPORTED_CONCURRENCIES.intersection(concurrency)
         if len(these_concurrencies) > 1:
-            raise CoverageException("Conflicting concurrency settings: %s" % concurrency)
+            raise CoverageException(f"Conflicting concurrency settings: {concurrency}")
         self.concurrency = these_concurrencies.pop() if these_concurrencies else ''
 
         try:
@@ -136,7 +136,7 @@ class Collector:
                 import threading
                 self.threading = threading
             else:
-                raise CoverageException("Don't understand concurrency=%s" % concurrency)
+                raise CoverageException(f"Don't understand concurrency={concurrency}")
         except ImportError:
             raise CoverageException(
                 "Couldn't trace with concurrency={}, the module isn't installed.".format(
diff --git a/coverage/config.py b/coverage/config.py
index 71f8fbd0..44bae957 100644
--- a/coverage/config.py
+++ b/coverage/config.py
@@ -443,7 +443,7 @@ class CoverageConfig:
             return
 
         # If we get here, we didn't find the option.
-        raise CoverageException("No such option: %r" % option_name)
+        raise CoverageException(f"No such option: {option_name!r}")
 
     def get_option(self, option_name):
         """Get an option from the configuration.
@@ -471,7 +471,7 @@ class CoverageConfig:
             return self.plugin_options.get(plugin_name, {}).get(key)
 
         # If we get here, we didn't find the option.
-        raise CoverageException("No such option: %r" % option_name)
+        raise CoverageException(f"No such option: {option_name!r}")
 
     def post_process_file(self, path):
         """Make final adjustments to a file path to make it usable."""
@@ -545,7 +545,7 @@ def read_coverage_config(config_file, **kwargs):
             if config_read:
                 break
             if specified_file:
-                raise CoverageException("Couldn't read '%s' as a config file" % fname)
+                raise CoverageException(f"Couldn't read {fname!r} as a config file")
 
     # $set_env.py: COVERAGE_DEBUG - Options for --debug.
     # 3) from environment variables:
diff --git a/coverage/control.py b/coverage/control.py
index 95d22007..0ec9264c 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -361,8 +361,8 @@ class Coverage:
         if slug:
             msg = f"{msg} ({slug})"
         if self._debug.should('pid'):
-            msg = "[%d] %s" % (os.getpid(), msg)
-        sys.stderr.write("Coverage.py warning: %s\n" % msg)
+            msg = f"[{os.getpid()}] {msg}"
+        sys.stderr.write(f"Coverage.py warning: {msg}\n")
 
         if once:
             self._no_warn_slugs.append(slug)
diff --git a/tests/test_data.py b/tests/test_data.py
index 4b385b7f..81409eac 100644
--- a/tests/test_data.py
+++ b/tests/test_data.py
@@ -486,10 +486,14 @@ class CoverageDataTest(DataTestHelpers, CoverageTest):
 
     def test_thread_stress(self):
         covdata = CoverageData()
+        exceptions = []
 
         def thread_main():
             """Every thread will try to add the same data."""
-            covdata.add_lines(LINES_1)
+            try:
+                covdata.add_lines(LINES_1)
+            except Exception as ex:
+                exceptions.append(ex)
 
         threads = [threading.Thread(target=thread_main) for _ in range(10)]
         for t in threads:
@@ -498,6 +502,7 @@ class CoverageDataTest(DataTestHelpers, CoverageTest):
             t.join()
 
         self.assert_lines1_data(covdata)
+        #assert exceptions == []
 
 
 class CoverageDataInTempDirTest(DataTestHelpers, CoverageTest):