Use f-strings where possible

Replaces str.format, which is less readable due to its separation of
format and arguments.

11 files changed, 63 insertions, 60 deletions

diff --git a/crocoite/behavior.py b/crocoite/behavior.py
index 321b65c..7f3a3a0 100644
--- a/crocoite/behavior.py
+++ b/crocoite/behavior.py
@@ -59,7 +59,7 @@ class Script:
             self.data = pkg_resources.resource_string (__name__, os.path.join ('data', path)).decode (encoding)
 
     def __repr__ (self):
-        return '<Script {}>'.format (self.path)
+        return f'<Script {self.path}>'
 
     def __str__ (self):
         return self.data
@@ -89,7 +89,7 @@ class Behavior:
         return True
 
     def __repr__ (self):
-        return '<Behavior {}>'.format (self.name)
+        return f'<Behavior {self.name}>'
 
     async def onload (self):
         """ After loading the page started """
@@ -138,7 +138,7 @@ class JsOnload (Behavior):
         constructor = result['objectId']
 
         if self.options:
-            yield Script.fromStr (json.dumps (self.options, indent=2), '{}/options'.format (self.script.path))
+            yield Script.fromStr (json.dumps (self.options, indent=2), f'{self.script.path}/options')
         result = await tab.Runtime.callFunctionOn (
                 functionDeclaration='function(options){return new this(options);}',
                 objectId=constructor,
@@ -231,9 +231,9 @@ class DomSnapshot (Behavior):
             if url in haveUrls:
                 # ignore duplicate URLs. they are usually caused by
                 # javascript-injected iframes (advertising) with no(?) src
-                self.logger.warning ('have DOM snapshot for URL {}, ignoring'.format (url))
+                self.logger.warning (f'have DOM snapshot for URL {url}, ignoring')
             elif url.scheme in ('http', 'https'):
-                self.logger.debug ('saving DOM snapshot for url {}, base {}'.format (doc['documentURL'], doc['baseURL']))
+                self.logger.debug (f'saving DOM snapshot for url {url}, base {doc["baseURL"]}')
                 haveUrls.add (url)
                 walker = ChromeTreeWalker (doc)
                 # remove script, to make the page static and noscript, because at the
diff --git a/crocoite/browser.py b/crocoite/browser.py
index 1c7ac3b..3de61f0 100644
--- a/crocoite/browser.py
+++ b/crocoite/browser.py
@@ -48,7 +48,7 @@ class Item:
         self.requestBody = None
 
     def __repr__ (self):
-        return '<Item {}>'.format (self.url)
+        return f'<Item {self.url}>'
 
     @property
     def request (self):
diff --git a/crocoite/controller.py b/crocoite/controller.py
index 53cb08d..504fa23 100644
--- a/crocoite/controller.py
+++ b/crocoite/controller.py
@@ -248,7 +248,7 @@ class DepthLimit (RecursionPolicy):
             return urls
 
     def __repr__ (self):
-        return '<DepthLimit {}>'.format (self.maxdepth)
+        return f'<DepthLimit {self.maxdepth}>'
 
 class PrefixLimit (RecursionPolicy):
     """
diff --git a/crocoite/devtools.py b/crocoite/devtools.py
index e62d4e0..fd56896 100644
--- a/crocoite/devtools.py
+++ b/crocoite/devtools.py
@@ -26,6 +26,7 @@ import json, asyncio, logging, os
 from tempfile import mkdtemp
 import shutil
 import aiohttp, websockets
+from yarl import URL
 
 from .util import StrJsonEncoder
 
@@ -42,7 +43,7 @@ class Browser:
     __slots__ = ('session', 'url', 'tab', 'loop')
 
     def __init__ (self, url, loop=None):
-        self.url = url
+        self.url = URL (url)
         self.session = None
         self.tab = None
         self.loop = loop
@@ -50,7 +51,7 @@ class Browser:
     async def __aiter__ (self):
         """ List all tabs """
         async with aiohttp.ClientSession (loop=self.loop) as session:
-            async with session.get ('{}/json/list'.format (self.url)) as r:
+            async with session.get (self.url.with_path ('/json/list')) as r:
                 resp = await r.json ()
                 for tab in resp:
                     if tab['type'] == 'page':
@@ -61,7 +62,7 @@ class Browser:
         assert self.tab is None
         assert self.session is None
         self.session = aiohttp.ClientSession (loop=self.loop)
-        async with self.session.get ('{}/json/new'.format (self.url)) as r:
+        async with self.session.get (self.url.with_path ('/json/new')) as r:
             resp = await r.json ()
             self.tab = await Tab.create (**resp)
             return self.tab
@@ -70,7 +71,7 @@ class Browser:
         assert self.tab is not None
         assert self.session is not None
         await self.tab.close ()
-        async with self.session.get ('{}/json/close/{}'.format (self.url, self.tab.id)) as r:
+        async with self.session.get (self.url.with_path (f'/json/close/{self.tab.id}')) as r:
             resp = await r.text ()
             assert resp == 'Target is closing'
         self.tab = None
@@ -103,13 +104,13 @@ class TabFunction:
         return hash (self.name)
 
     def __getattr__ (self, k):
-        return TabFunction ('{}.{}'.format (self.name, k), self.tab)
+        return TabFunction (f'{self.name}.{k}', self.tab)
 
     async def __call__ (self, **kwargs):
         return await self.tab (self.name, **kwargs)
 
     def __repr__ (self):
-        return '<TabFunction {}>'.format (self.name)
+        return f'<TabFunction {self.name}>'
 
 class TabException (Exception):
     pass
@@ -156,7 +157,7 @@ class Tab:
         self.msgid += 1
         message = {'method': method, 'params': kwargs, 'id': msgid}
         t = self.transactions[msgid] = {'event': asyncio.Event (), 'result': None}
-        logger.debug ('← {}'.format (message))
+        logger.debug (f'← {message}')
         await self.ws.send (json.dumps (message, cls=StrJsonEncoder))
         await t['event'].wait ()
         ret = t['result']
@@ -191,7 +192,7 @@ class Tab:
                 # right now we cannot recover from this
                 await markCrashed (e)
                 break
-            logger.debug ('→ {}'.format (msg))
+            logger.debug (f'→ {msg}')
             if 'id' in msg:
                 msgid = msg['id']
                 t = self.transactions.get (msgid, None)
@@ -272,7 +273,7 @@ class Process:
         # see https://github.com/GoogleChrome/chrome-launcher/blob/master/docs/chrome-flags-for-tools.md
         args = [self.binary,
                 '--window-size={},{}'.format (*self.windowSize),
-                '--user-data-dir={}'.format (self.userDataDir), # use temporory user dir
+                f'--user-data-dir={self.userDataDir}', # use temporory user dir
                 '--no-default-browser-check',
                 '--no-first-run', # don’t show first run screen
                 '--disable-breakpad', # no error reports
@@ -317,7 +318,7 @@ class Process:
         if port is None:
             raise Exception ('Chrome died on us.')
 
-        return 'http://localhost:{}'.format (port)
+        return URL.build(scheme='http', host='localhost', port=port)
 
     async def __aexit__ (self, *exc):
         self.p.terminate ()
@@ -330,7 +331,7 @@ class Passthrough:
     __slots__ = ('url', )
 
     def __init__ (self, url):
-        self.url = url
+        self.url = URL (url)
 
     async def __aenter__ (self):
         return self.url
diff --git a/crocoite/irc.py b/crocoite/irc.py
index 99485e4..96d0e3e 100644
--- a/crocoite/irc.py
+++ b/crocoite/irc.py
@@ -53,7 +53,7 @@ def prettyBytes (b):
     while b >= 1024 and len (prefixes) > 1:
         b /= 1024
         prefixes.pop (0)
-    return '{:.1f} {}'.format (b, prefixes[0])
+    return f'{b:.1f} {prefixes[0]}'
 
 def isValidUrl (s):
     url = urlsplit (s)
@@ -104,16 +104,13 @@ class Job:
     def formatStatus (self):
         stats = self.stats
         rstats = self.rstats
-        return '{} ({}) {}. {} pages finished, {} pending; {} crashed, {} requests, {} failed, {} received.'.format (
-                self.url,
-                self.id,
-                self.status.name,
-                rstats.get ('have', 0),
-                rstats.get ('pending', 0),
-                stats.get ('crashed', 0),
-                stats.get ('requests', 0),
-                stats.get ('failed', 0),
-                prettyBytes (stats.get ('bytesRcv', 0)))
+        return (f"{self.url} ({self.id}) {self.status.name}. "
+                "{rstats.get ('have', 0)} pages finished, "
+                "{rstats.get ('pending', 0)} pending; "
+                "{stats.get ('crashed', 0)} crashed, "
+                "{stats.get ('requests', 0)} requests, "
+                "{stats.get ('failed', 0)} failed, "
+                "{prettyBytes (stats.get ('bytesRcv', 0))} received.")
 
 class NickMode(Enum):
     operator = '@'
@@ -138,7 +135,7 @@ class User:
         return hash (self.name)
 
     def __repr__ (self):
-        return '<User {} {}>'.format (self.name, self.modes)
+        return f'<User {self.name} {self.modes}>'
 
     @classmethod
     def fromName (cls, name):
@@ -159,7 +156,8 @@ class ReplyContext:
         self.user = user
 
     def __call__ (self, message):
-        self.client.send ('PRIVMSG', target=self.target, message='{}: {}'.format (self.user.name, message))
+        self.client.send ('PRIVMSG', target=self.target,
+                message=f'{self.user.name}: {message}')
 
 class RefCountEvent:
     """
@@ -321,10 +319,10 @@ class ArgparseBot (bottom.Client):
             try:
                 args = self.parser.parse_args (command)
             except Exception as e:
-                reply ('{} -- {}'.format (e.args[1], e.args[0].format_usage ()))
+                reply (f'{e.args[1]} -- {e.args[0].format_usage ()}')
                 return
             if not args:
-                reply ('Sorry, I don’t understand {}'.format (command))
+                reply (f'Sorry, I don’t understand {command}')
                 return
 
             if self._quit.armed and not getattr (args, 'allowOnShutdown', False):
@@ -363,7 +361,7 @@ def jobExists (func):
         reply = kwargs.get ('reply')
         j = self.jobs.get (args.id, None)
         if not j:
-            reply ('Job {} is unknown'.format (args.id))
+            reply (f'Job {args.id} is unknown')
         else:
             ret = await func (self, job=j, **kwargs)
             return ret
@@ -426,7 +424,7 @@ class Chromebot (ArgparseBot):
                 'concurrency': args.concurrency,
                 }
         strargs = ', '.join (map (lambda x: '{}={}'.format (*x), showargs.items ()))
-        reply ('{} has been queued as {} with {}'.format (args.url, j.id, strargs))
+        reply (f'{args.url} has been queued as {j.id} with {strargs}')
         logger.info ('queue', user=user.name, url=args.url, cmdline=cmdline,
                 uuid='36cc34a6-061b-4cc5-84a9-4ab6552c8d75')
 
diff --git a/crocoite/test_browser.py b/crocoite/test_browser.py
index 8a8d81f..6015a2f 100644
--- a/crocoite/test_browser.py
+++ b/crocoite/test_browser.py
@@ -142,7 +142,7 @@ async def itemsLoaded (l, items):
         assert item.chromeResponse is not None
         golden = items.pop (item.url.path)
         if not golden:
-            assert False, 'url {} not supposed to be fetched'.format (item.url)
+            assert False, f'url {item.url} not supposed to be fetched'
         assert item.failed == golden.failed
         if item.failed:
             # response will be invalid if request failed
diff --git a/crocoite/test_devtools.py b/crocoite/test_devtools.py
index 74d223f..3993edd 100644
--- a/crocoite/test_devtools.py
+++ b/crocoite/test_devtools.py
@@ -24,7 +24,8 @@ import pytest
 from aiohttp import web
 import websockets
 
-from .devtools import Browser, Tab, MethodNotFound, Crashed, InvalidParameter, Process, Passthrough
+from .devtools import Browser, Tab, MethodNotFound, Crashed, \
+        InvalidParameter, Process, Passthrough
 
 @pytest.fixture
 async def browser ():
@@ -73,8 +74,10 @@ async def test_tab_close (browser):
 
 @pytest.mark.asyncio
 async def test_tab_notify_enable_disable (tab):
-    """ Make sure enabling/disabling notifications works for all known namespaces """
-    for name in ('Debugger', 'DOM', 'Log', 'Network', 'Page', 'Performance', 'Profiler', 'Runtime', 'Security'):
+    """ Make sure enabling/disabling notifications works for all known
+    namespaces """
+    for name in ('Debugger', 'DOM', 'Log', 'Network', 'Page', 'Performance',
+            'Profiler', 'Runtime', 'Security'):
         f = getattr (tab, name)
         await f.enable ()
         await f.disable ()
@@ -149,7 +152,8 @@ async def test_tab_function (tab):
 
 @pytest.mark.asyncio
 async def test_tab_function_hash (tab):
-    d = {tab.Network.enable: 1, tab.Network.disable: 2, tab.Page: 3, tab.Page.enable: 4}
+    d = {tab.Network.enable: 1, tab.Network.disable: 2, tab.Page: 3,
+            tab.Page.enable: 4}
     assert len (d) == 4
 
 @pytest.mark.asyncio
@@ -168,5 +172,5 @@ async def test_passthrough ():
 
     url = 'http://localhost:12345'
     async with Passthrough (url) as u:
-        assert u == url
+        assert str (u) == url
 
diff --git a/crocoite/test_tools.py b/crocoite/test_tools.py
index c320ad9..106aa59 100644
--- a/crocoite/test_tools.py
+++ b/crocoite/test_tools.py
@@ -97,7 +97,7 @@ def test_different_payload(writer):
 
         httpHeaders = StatusAndHeaders('200 OK', {}, protocol='HTTP/1.1')
         record = writer.create_warc_record ('http://example.com/', 'response',
-                payload=BytesIO('data{}'.format(i).encode ('utf8')),
+                payload=BytesIO(f'data{i}'.encode ('utf8')),
                 warc_headers_dict=warcHeaders, http_headers=httpHeaders)
         records.append (record)
 
diff --git a/crocoite/tools.py b/crocoite/tools.py
index 84c6f44..9c5d836 100644
--- a/crocoite/tools.py
+++ b/crocoite/tools.py
@@ -67,7 +67,7 @@ def mergeWarc (files, output):
                                 'id': rid, 'date': headers.get_header('WARC-Date')}
                         unique += 1
                     else:
-                        logging.debug ('Record {} is duplicate of {}'.format (rid, dup['id']))
+                        logging.debug (f'Record {rid} is duplicate of {dup["id"]}')
                         # Payload may be identical, but HTTP headers are
                         # (probably) not. Include them.
                         record = writer.create_revisit_record (
@@ -80,7 +80,7 @@ def mergeWarc (files, output):
                 else:
                     unique += 1
                 writer.write_record (record)
-    logging.info ('Wrote {} unique records, {} revisits'.format (unique, revisit))
+    logging.info (f'Wrote {unique} unique records, {revisit} revisits')
 
 def mergeWarcCli():
     parser = argparse.ArgumentParser(description='Merge WARCs, reads filenames from stdin.')
@@ -116,12 +116,12 @@ def extractScreenshot ():
             urlSanitized = headers.get_header('WARC-Target-URI').replace ('/', '_')
             xoff = 0
             yoff = int (headers.get_header ('X-Crocoite-Screenshot-Y-Offset'))
-            outpath = '{}-{}-{}-{}.png'.format (args.prefix, urlSanitized, xoff, yoff)
+            outpath = f'{args.prefix}-{urlSanitized}-{xoff}-{yoff}.png'
             if args.force or not os.path.exists (outpath):
                 with open (outpath, 'wb') as out:
                     shutil.copyfileobj (record.raw_stream, out)
             else:
-                print ('not overwriting {}'.format (outpath))
+                print (f'not overwriting {outputh}')
 
 class Errata:
     __slots__ = ('uuid', 'description', 'affects')
@@ -145,8 +145,7 @@ class Errata:
         return all (matchedAll)
 
     def __repr__ (self):
-        return '{}({!r}, {!r}, {!r})'.format (self.__class__.__name__,
-                self.uuid, self.description, self.affects)
+        return f'{self.__class__.__name__}({self.uuid!r}, {self.description!r}, {self.affects!r})'
 
     @property
     def fixable (self):
@@ -180,7 +179,7 @@ def makeReport (fd):
                 pass
 
 def errata ():
-    parser = argparse.ArgumentParser(description='Show/fix erratas for WARCs generated by {}.'.format (__package__))
+    parser = argparse.ArgumentParser(description=f'Show/fix erratas for WARCs generated by {__package__}.')
     parser.add_argument('input', type=argparse.FileType ('rb'), help='Input WARC')
 
     args = parser.parse_args()
diff --git a/crocoite/util.py b/crocoite/util.py
index eebe909..5bced53 100644
--- a/crocoite/util.py
+++ b/crocoite/util.py
@@ -48,8 +48,8 @@ def packageUrl (path):
 async def getFormattedViewportMetrics (tab):
     layoutMetrics = await tab.Page.getLayoutMetrics ()
     # XXX: I’m not entirely sure which one we should use here
-    return '{}x{}'.format (layoutMetrics['layoutViewport']['clientWidth'],
-                layoutMetrics['layoutViewport']['clientHeight'])
+    viewport = layoutMetrics['layoutViewport']
+    return f"{viewport['clientWidth']}x{viewport['clientHeight']}"
 
 def getSoftwareInfo ():
     """ Get software info for inclusion into warcinfo """
diff --git a/crocoite/warc.py b/crocoite/warc.py
index 21a99aa..04dd871 100644
--- a/crocoite/warc.py
+++ b/crocoite/warc.py
@@ -87,7 +87,7 @@ class WarcHandler (EventHandler):
         url = item.url
 
         path = url.relative().with_fragment(None)
-        httpHeaders = StatusAndHeaders('{} {} HTTP/1.1'.format (req['method'], path),
+        httpHeaders = StatusAndHeaders(f'{req["method"]} {path} HTTP/1.1',
                 item.requestHeaders, protocol='HTTP/1.1', is_http_request=True)
         initiator = item.initiator
         warcHeaders = {
@@ -144,8 +144,8 @@ class WarcHandler (EventHandler):
         else:
             warcHeaders['X-Chrome-Base64Body'] = str (base64Encoded)
 
-        httpHeaders = StatusAndHeaders('{} {}'.format (resp['status'],
-                item.statusText), item.responseHeaders,
+        httpHeaders = StatusAndHeaders(f'{resp["status"]} {item.statusText}',
+                item.responseHeaders,
                 protocol='HTTP/1.1')
 
         # Content is saved decompressed and decoded, remove these headers
@@ -163,7 +163,7 @@ class WarcHandler (EventHandler):
             httpHeaders.replace_header ('content-type', contentType)
 
         if rawBody is not None:
-            httpHeaders.replace_header ('content-length', '{:d}'.format (len (rawBody)))
+            httpHeaders.replace_header ('content-length', str (len (rawBody)))
             bodyIo = BytesIO (rawBody)
         else:
             bodyIo = BytesIO ()
@@ -178,9 +178,10 @@ class WarcHandler (EventHandler):
     def _writeScript (self, item):
         writer = self.writer
         encoding = 'utf-8'
-        self.writeRecord (packageUrl ('script/{}'.format (item.path)), 'metadata',
+        self.writeRecord (packageUrl (f'script/{item.path}'), 'metadata',
                 payload=BytesIO (str (item).encode (encoding)),
-                warc_headers_dict={'Content-Type': 'application/javascript; charset={}'.format (encoding)})
+                warc_headers_dict={'Content-Type':
+                f'application/javascript; charset={encoding}'})
 
     def _writeItem (self, item):
         if item.failed:
@@ -195,7 +196,7 @@ class WarcHandler (EventHandler):
         if refersTo:
             headers['WARC-Refers-To'] = refersTo
         else:
-            self.logger.error ('No document record found for {}'.format (url))
+            self.logger.error (f'No document record found for {url}')
         return headers
 
     def _writeDomSnapshot (self, item):
@@ -234,7 +235,7 @@ class WarcHandler (EventHandler):
         self.log.seek (0)
         # XXX: we should use the type continuation here
         self.writeRecord (packageUrl ('log'), 'resource', payload=self.log,
-                warc_headers_dict={'Content-Type': 'text/plain; encoding={}'.format (self.logEncoding)})
+                warc_headers_dict={'Content-Type': f'text/plain; encoding={self.logEncoding}'})
         self.log = BytesIO ()
 
     def _writeLog (self, item):
@@ -262,5 +263,5 @@ class WarcHandler (EventHandler):
                 break
 
         if not processed:
-            self.logger.debug ('unknown event {}'.format (repr (item)))
+            self.logger.debug (f'unknown event {item!r}')