Switch old-style string formattings to new '.format()'

17 files changed, 81 insertions, 80 deletions

diff --git a/buildstream/_artifactcache/pushreceive.py b/buildstream/_artifactcache/pushreceive.py
index 8d2d3fb0b..9aef842a8 100644
--- a/buildstream/_artifactcache/pushreceive.py
+++ b/buildstream/_artifactcache/pushreceive.py
@@ -67,8 +67,8 @@ def msg_byteorder(sys_byteorder=sys.byteorder):
     elif sys_byteorder == 'big':
         return 'B'
     else:
-        raise PushException('Unrecognized system byteorder %s'
-                            % sys_byteorder)
+        raise PushException('Unrecognized system byteorder {}'
+                            .format(sys_byteorder))
 
 
 def sys_byteorder(msg_byteorder):
@@ -77,8 +77,8 @@ def sys_byteorder(msg_byteorder):
     elif msg_byteorder == 'B':
         return 'big'
     else:
-        raise PushException('Unrecognized message byteorder %s'
-                            % msg_byteorder)
+        raise PushException('Unrecognized message byteorder {}'
+                            .format(msg_byteorder))
 
 
 def ostree_object_path(repo, obj):
@@ -220,18 +220,18 @@ class PushMessageReader(object):
 
     def decode_header(self, header):
         if len(header) != HEADER_SIZE:
-            raise Exception('Header is %d bytes, not %d' % (len(header), HEADER_SIZE))
+            raise Exception('Header is {:d} bytes, not {:d}'.format(len(header), HEADER_SIZE))
         order = sys_byteorder(chr(header[0]))
         version = int(header[1])
         if version != PROTO_VERSION:
-            raise Exception('Unsupported protocol version %d' % version)
+            raise Exception('Unsupported protocol version {:d}'.format(version))
         cmdtype = PushCommandType(int(header[2]))
         vlen = int.from_bytes(header[3:], order)
         return order, version, cmdtype, vlen
 
     def decode_message(self, message, size, order):
         if len(message) != size:
-            raise Exception('Expected %d bytes, but got %d' % (size, len(message)))
+            raise Exception('Expected {:d} bytes, but got {:d}'.format(size, len(message)))
         data = GLib.Bytes.new(message)
         variant = GLib.Variant.new_from_bytes(GLib.VariantType.new('a{sv}'),
                                               data, False)
@@ -317,7 +317,7 @@ def parse_remote_location(remotepath, remote_port):
     if url.netloc:
         if url.scheme != 'ssh':
             raise PushException('Only URL scheme ssh is allowed, '
-                                'not "%s"' % url.scheme)
+                                'not "{}"'.format(url.scheme))
         remote_host = url.hostname
         remote_user = url.username
         remote_repo = url.path
@@ -333,9 +333,9 @@ def parse_remote_location(remotepath, remote_port):
             remainder = parts[0]
         parts = remainder.split(':', 1)
         if len(parts) != 2:
-            raise PushException('Remote repository "%s" does not '
+            raise PushException('Remote repository "{}" does not '
                                 'contain a hostname and path separated '
-                                'by ":"' % remotepath)
+                                'by ":"'.format(remotepath))
         remote_host, remote_repo = parts
 
     return remote_host, remote_user, remote_repo, remote_port
@@ -407,15 +407,15 @@ class OSTreePusher(object):
             _, commit = self.repo.load_variant_if_exists(OSTree.ObjectType.COMMIT,
                                                          parent)
             if commit is None:
-                raise PushException('Shallow history from commit %s does '
-                                    'not contain remote commit %s' % (local, remote))
+                raise PushException('Shallow history from commit {} does '
+                                    'not contain remote commit {}'.format(local, remote))
             parent = OSTree.commit_get_parent(commit)
             if parent is None:
                 break
         if remote is not None and parent != remote:
             self.writer.send_done()
-            raise PushExistsException('Remote commit %s not descendent of '
-                                      'commit %s' % (remote, local))
+            raise PushExistsException('Remote commit {} not descendent of '
+                                      'commit {}'.format(remote, local))
 
     def needed_objects(self, commits):
         objects = set()
diff --git a/buildstream/_frontend/main.py b/buildstream/_frontend/main.py
index 4e00a2be1..46cc7a9ca 100644
--- a/buildstream/_frontend/main.py
+++ b/buildstream/_frontend/main.py
@@ -497,7 +497,7 @@ def shell(app, element, sysroot, build, command):
         sys.exit(exitcode)
     except BstError as e:
         click.echo("")
-        click.echo("Errors shelling into this pipeline: %s" % str(e))
+        click.echo("Errors shelling into this pipeline: {}".format(str(e)))
         sys.exit(-1)
 
 
@@ -773,7 +773,7 @@ class App():
             self.context = Context(self.main_options['option'])
             self.context.load(config)
         except BstError as e:
-            click.echo("Error loading user configuration: %s" % str(e))
+            click.echo("Error loading user configuration: {}".format(str(e)))
             sys.exit(-1)
 
         # Override things in the context from our command line options,
@@ -831,7 +831,7 @@ class App():
         try:
             self.project = Project(directory, self.context)
         except BstError as e:
-            click.echo("Error loading project: %s" % str(e))
+            click.echo("Error loading project: {}".format(str(e)))
             sys.exit(-1)
 
         try:
@@ -844,7 +844,7 @@ class App():
                                      remote_ticker=self.remote_ticker,
                                      cache_ticker=self.cache_ticker)
         except BstError as e:
-            click.echo("Error loading pipeline: %s" % str(e))
+            click.echo("Error loading pipeline: {}".format(str(e)))
             sys.exit(-1)
 
         # Create our status printer, only available in interactive
diff --git a/buildstream/_fuse/fuse.py b/buildstream/_fuse/fuse.py
index f0ad96fba..89173ba11 100644
--- a/buildstream/_fuse/fuse.py
+++ b/buildstream/_fuse/fuse.py
@@ -268,7 +268,7 @@ elif _system == 'Linux':
             ('st_ctimespec', c_timespec),
             ('st_ino', c_ulonglong)]
 else:
-    raise NotImplementedError('%s is not supported.' % _system)
+    raise NotImplementedError('{} is not supported.'.format(_system))
 
 
 class c_statvfs(Structure):
@@ -507,7 +507,7 @@ class FUSE(object):
             if isinstance(value, bool):
                 if value is True: yield key
             else:
-                yield '%s=%s' % (key, value)
+                yield '{}={}'.format(key, value)
 
     @staticmethod
     def _wrapper(func, *args, **kwargs):
@@ -608,7 +608,7 @@ class FUSE(object):
 
         retsize = len(ret)
         assert retsize <= size, \
-            'actual amount read %d greater than expected %d' % (retsize, size)
+            'actual amount read {:d} greater than expected {:d}'.format(retsize, size)
 
         data = create_string_buffer(ret, retsize)
         memmove(buf, data, retsize)
diff --git a/buildstream/_loader.py b/buildstream/_loader.py
index 9a3fd5eaa..f086625d5 100644
--- a/buildstream/_loader.py
+++ b/buildstream/_loader.py
@@ -154,8 +154,8 @@ def extract_depends_from_node(owner, data):
             elif dep_type not in [Symbol.BUILD, Symbol.RUNTIME]:
                 provenance = _yaml.node_get_provenance(dep, key=Symbol.TYPE)
                 raise LoadError(LoadErrorReason.INVALID_DATA,
-                                "%s: Dependency type '%s' is not 'build', 'runtime' or 'all'" %
-                                (str(provenance), dep_type))
+                                "{}: Dependency type '{}' is not 'build', 'runtime' or 'all'"
+                                .format(str(provenance), dep_type))
 
             filename = _yaml.node_get(dep, str, Symbol.FILENAME)
             dependency = Dependency(owner, filename, filename=filename,
@@ -166,8 +166,8 @@ def extract_depends_from_node(owner, data):
             provenance = _yaml.node_get_provenance(data, key=Symbol.DEPENDS, indices=[index])
 
             raise LoadError(LoadErrorReason.INVALID_DATA,
-                            "%s: List '%s' element %d is not a list or dict" %
-                            (str(provenance), Symbol.DEPENDS, index))
+                            "{}: List '{}' element {:d} is not a list or dict"
+                            .format(str(provenance), Symbol.DEPENDS, index))
 
         output_deps.append(dependency)
 
@@ -198,9 +198,9 @@ class Loader():
                 # XXX Should this just be an assertion ?
                 # Expect that the caller gives us the right thing at least ?
                 raise LoadError(LoadErrorReason.INVALID_DATA,
-                                "Target '%s' was not specified as a relative "
-                                "path to the base project directory: %s" %
-                                (filename, basedir))
+                                "Target '{}' was not specified as a relative "
+                                "path to the base project directory: {}"
+                                .format(filename, basedir))
 
         self.options = options   # Project options (OptionPool)
         self.basedir = basedir   # Base project directory
@@ -314,8 +314,8 @@ class Loader():
 
         if check_elements.get(element_name) is not None:
             raise LoadError(LoadErrorReason.CIRCULAR_DEPENDENCY,
-                            "Circular dependency detected for element: %s" %
-                            element.filename)
+                            "Circular dependency detected for element: {}"
+                            .format(element.filename))
 
         # Push / Check each dependency / Pop
         check_elements[element_name] = True
diff --git a/buildstream/_options/optionpool.py b/buildstream/_options/optionpool.py
index 387080110..90a404bfb 100644
--- a/buildstream/_options/optionpool.py
+++ b/buildstream/_options/optionpool.py
@@ -138,7 +138,7 @@ class OptionPool():
         # Variables must be resolved at this point.
         #
         try:
-            template_string = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % expression
+            template_string = "{{% if {} %}} True {{% else %}} False {{% endif %}}".format(expression)
             template = self.environment.from_string(template_string)
             context = template.new_context(self.variables, shared=True)
             result = template.root_render_func(context)
diff --git a/buildstream/_ostree.py b/buildstream/_ostree.py
index 794c57df3..736269169 100644
--- a/buildstream/_ostree.py
+++ b/buildstream/_ostree.py
@@ -271,7 +271,8 @@ def fetch(repo, remote="origin", ref=None, progress=None):
             else:
                 percent = (fetched * 1.0 / requested) * 100
 
-            progress(percent, "Receiving objects: %d%% (%d/%d) %s" % (percent, fetched, requested, formatted_bytes))
+            progress(percent,
+                     "Receiving objects: {:d}% ({:d}/{:d}) {}".format(percent, fetched, requested, formatted_bytes))
         else:
             progress(100.0, "Writing Objects")
 
diff --git a/buildstream/_variables.py b/buildstream/_variables.py
index 15e5ecac1..fa73006e6 100644
--- a/buildstream/_variables.py
+++ b/buildstream/_variables.py
@@ -159,7 +159,7 @@ class Variables():
                         summary += line.format(unmatched=unmatch, variable=var, provenance=provenance)
 
                 raise LoadError(LoadErrorReason.UNRESOLVED_VARIABLE,
-                                "Failed to resolve one or more variable:\n%s" % summary)
+                                "Failed to resolve one or more variable:\n{}".format(summary))
 
             last_unmatched = unmatched
 
diff --git a/buildstream/_yaml.py b/buildstream/_yaml.py
index b4693b836..eb6719360 100644
--- a/buildstream/_yaml.py
+++ b/buildstream/_yaml.py
@@ -53,7 +53,7 @@ class Provenance():
 
     # Convert a Provenance to a string for error reporting
     def __str__(self):
-        return "%s [line %d column %d]" % (self.filename, self.line, self.col)
+        return "{} [line {:d} column {:d}]".format(self.filename, self.line, self.col)
 
     # Abstract method
     def clone(self):
@@ -152,9 +152,9 @@ class CompositeTypeError(CompositeError):
     def __init__(self, path, expected_type, actual_type):
         super(CompositeTypeError, self).__init__(
             path,
-            "Error compositing dictionary key '%s', expected source type '%s' "
-            "but received type '%s'" %
-            (path, expected_type.__name__, actual_type.__name__))
+            "Error compositing dictionary key '{}', expected source type '{}' "
+            "but received type '{}'"
+            .format(path, expected_type.__name__, actual_type.__name__))
         self.expected_type = expected_type
         self.actual_type = actual_type
 
@@ -180,7 +180,7 @@ def load(filename, shortname=None, copy_tree=False):
             return load_data(f, shortname=shortname, copy_tree=copy_tree)
     except FileNotFoundError as e:
         raise LoadError(LoadErrorReason.MISSING_FILE,
-                        "Could not find file at %s" % filename) from e
+                        "Could not find file at {}".format(filename)) from e
 
 
 # Like load(), but doesnt require the data to be in a file
@@ -191,7 +191,7 @@ def load_data(data, shortname=None, copy_tree=False):
         contents = yaml.load(data, yaml.loader.RoundTripLoader)
     except (yaml.scanner.ScannerError, yaml.composer.ComposerError, yaml.parser.ParserError) as e:
         raise LoadError(LoadErrorReason.INVALID_YAML,
-                        "Malformed YAML:\n\n%s\n\n%s\n" % (e.problem, e.problem_mark)) from e
+                        "Malformed YAML:\n\n{}\n\n{}\n".format(e.problem, e.problem_mark)) from e
 
     if not isinstance(contents, dict):
         # Special case allowance for None, when the loaded file has only comments in it.
@@ -199,8 +199,8 @@ def load_data(data, shortname=None, copy_tree=False):
             contents = {}
         else:
             raise LoadError(LoadErrorReason.INVALID_YAML,
-                            "YAML file has content of type '%s' instead of expected type 'dict': %s" %
-                            (type(contents).__name__, shortname))
+                            "YAML file has content of type '{}' instead of expected type 'dict': {}"
+                            .format(type(contents).__name__, shortname))
 
     return node_decorated_copy(shortname, contents, copy_tree=copy_tree)
 
@@ -326,7 +326,7 @@ def node_get(node, expected_type, key, indices=[], default_value=None):
     provenance = node_get_provenance(node)
     if value is None:
         raise LoadError(LoadErrorReason.INVALID_DATA,
-                        "%s: Dictionary did not contain expected key '%s'" % (str(provenance), key))
+                        "{}: Dictionary did not contain expected key '{}'".format(str(provenance), key))
 
     path = key
     if indices:
@@ -334,7 +334,7 @@ def node_get(node, expected_type, key, indices=[], default_value=None):
         value = node_get(node, list, key)
         for index in indices:
             value = value[index]
-            path += '[%d]' % index
+            path += '[{:d}]'.format(index)
 
     if not isinstance(value, expected_type):
         # Attempt basic conversions if possible, typically we want to
@@ -359,8 +359,8 @@ def node_get(node, expected_type, key, indices=[], default_value=None):
         except (ValueError, TypeError):
             provenance = node_get_provenance(node, key=key, indices=indices)
             raise LoadError(LoadErrorReason.INVALID_DATA,
-                            "%s: Value of '%s' is not of the expected type '%s'" %
-                            (str(provenance), path, expected_type.__name__))
+                            "{}: Value of '{}' is not of the expected type '{}'"
+                            .format(str(provenance), path, expected_type.__name__))
 
     # Trim it at the bud, let all loaded strings from yaml be stripped of whitespace
     if isinstance(value, str):
@@ -757,11 +757,11 @@ def composite(target, source):
         if source_provenance:
             error_prefix = "{}: ".format(str(source_provenance))
         raise LoadError(LoadErrorReason.ILLEGAL_COMPOSITE,
-                        "%sExpected '%s' type for configuration '%s', instead received '%s'" %
-                        (error_prefix,
-                         e.expected_type.__name__,
-                         e.path,
-                         e.actual_type.__name__)) from e
+                        "{}Expected '{}' type for configuration '{}', instead received '{}'"
+                        .format(error_prefix,
+                                e.expected_type.__name__,
+                                e.path,
+                                e.actual_type.__name__)) from e
 
 
 # SanitizedDict is an OrderedDict that is dumped as unordered mapping.
diff --git a/buildstream/buildelement.py b/buildstream/buildelement.py
index a794e9844..0870c83ad 100644
--- a/buildstream/buildelement.py
+++ b/buildstream/buildelement.py
@@ -184,9 +184,9 @@ class BuildElement(Element):
             if not commands:
                 continue
 
-            with self.timed_activity("Running %s" % command_name):
+            with self.timed_activity("Running {}".format(command_name)):
                 for cmd in commands:
-                    self.status("Running %s" % command_name, detail=cmd)
+                    self.status("Running {}".format(command_name), detail=cmd)
 
                     # Note the -e switch to 'sh' means to exit with an error
                     # if any untested command fails.
diff --git a/buildstream/plugins/sources/git.py b/buildstream/plugins/sources/git.py
index d7a87c86c..4aca57ffb 100644
--- a/buildstream/plugins/sources/git.py
+++ b/buildstream/plugins/sources/git.py
@@ -104,8 +104,8 @@ class GitMirror():
                 try:
                     shutil.move(tmpdir, self.mirror)
                 except (shutil.Error, OSError) as e:
-                    raise SourceError("%s: Failed to move cloned git repository %s from '%s' to '%s'" %
-                                      (str(self.source), self.url, tmpdir, self.mirror)) from e
+                    raise SourceError("{}: Failed to move cloned git repository {} from '{}' to '{}'"
+                                      .format(str(self.source), self.url, tmpdir, self.mirror)) from e
 
     def fetch(self):
         self.source.call([self.source.host_git, 'fetch', 'origin', '--prune'],
@@ -126,8 +126,8 @@ class GitMirror():
 
     def assert_ref(self):
         if not self.has_ref():
-            raise SourceError("%s: expected ref '%s' was not found in git repository: '%s'" %
-                              (str(self.source), self.ref, self.url))
+            raise SourceError("{}: expected ref '{}' was not found in git repository: '{}'"
+                              .format(str(self.source), self.ref, self.url))
 
     def latest_commit(self, tracking):
         _, output = self.source.check_output(
@@ -212,14 +212,14 @@ class GitMirror():
 
             # fail if the commit hash is invalid
             if len(submodule_commit) != 40:
-                raise SourceError("%s: Error reading commit information for submodule '%s'" %
-                                  (str(self.source), submodule))
+                raise SourceError("{}: Error reading commit information for submodule '{}'"
+                                  .format(str(self.source), submodule))
 
             return submodule_commit
 
         else:
-            raise SourceError("%s: Failed to read commit information for submodule '%s'" %
-                              (str(self.source), submodule))
+            raise SourceError("{}: Failed to read commit information for submodule '{}'"
+                              .format(str(self.source), submodule))
 
 
 class GitSource(Source):
diff --git a/buildstream/plugins/sources/local.py b/buildstream/plugins/sources/local.py
index 02486dffb..d513b897e 100644
--- a/buildstream/plugins/sources/local.py
+++ b/buildstream/plugins/sources/local.py
@@ -50,7 +50,7 @@ class LocalSource(Source):
     def preflight(self):
         # Check if the configured file or directory really exists
         if not os.path.exists(self.fullpath):
-            raise SourceError("Specified path '%s' does not exist" % self.path)
+            raise SourceError("Specified path '{}' does not exist".format(self.path))
 
     def get_unique_key(self):
         # Get a list of tuples of the the project relative paths and fullpaths
diff --git a/buildstream/plugins/sources/patch.py b/buildstream/plugins/sources/patch.py
index 9da6ade40..8ff8b1162 100644
--- a/buildstream/plugins/sources/patch.py
+++ b/buildstream/plugins/sources/patch.py
@@ -53,9 +53,9 @@ class PatchSource(Source):
     def preflight(self):
         # Check if the configured file really exists
         if not os.path.exists(self.fullpath):
-            raise SourceError("Specified path '%s' does not exist" % self.path)
+            raise SourceError("Specified path '{}' does not exist".format(self.path))
         elif not os.path.isfile(self.fullpath):
-            raise SourceError("Specified path '%s' must be a file" % self.path)
+            raise SourceError("Specified path '{}' must be a file".format(self.path))
 
         # Check if patch is installed, get the binary at the same time
         self.host_patch = utils.get_host_tool("patch")
diff --git a/buildstream/source.py b/buildstream/source.py
index 5c97a5743..71aa7e358 100644
--- a/buildstream/source.py
+++ b/buildstream/source.py
@@ -150,7 +150,7 @@ class Source(Plugin):
         Returns:
            (:class:`.Consistency`): The source consistency
         """
-        raise ImplError("Source plugin '%s' does not implement get_consistency()" % self.get_kind())
+        raise ImplError("Source plugin '{}' does not implement get_consistency()".format(self.get_kind()))
 
     def get_ref(self):
         """Fetch the internal ref, however it is represented
@@ -164,7 +164,7 @@ class Source(Plugin):
            in a VCS or a tarball's checksum. Usually the reference is a string,
            but the plugin may choose to represent it with a tuple or such.
         """
-        raise ImplError("Source plugin '%s' does not implement get_ref()" % self.get_kind())
+        raise ImplError("Source plugin '{}' does not implement get_ref()".format(self.get_kind()))
 
     def set_ref(self, ref, node):
         """Applies the internal ref, however it is represented
@@ -177,7 +177,7 @@ class Source(Plugin):
         See :func:`~buildstream.source.Source.get_ref` for a discussion on
         the *ref* parameter.
         """
-        raise ImplError("Source plugin '%s' does not implement set_ref()" % self.get_kind())
+        raise ImplError("Source plugin '{}' does not implement set_ref()".format(self.get_kind()))
 
     def track(self):
         """Resolve a new ref from the plugin's track option
@@ -210,7 +210,7 @@ class Source(Plugin):
         Implementors should raise :class:`.SourceError` if the there is some
         network error or if the source reference could not be matched.
         """
-        raise ImplError("Source plugin '%s' does not implement fetch()" % self.get_kind())
+        raise ImplError("Source plugin '{}' does not implement fetch()".format(self.get_kind()))
 
     def stage(self, directory):
         """Stage the sources to a directory
@@ -227,7 +227,7 @@ class Source(Plugin):
         Implementors should raise :class:`.SourceError` when encountering
         some system error.
         """
-        raise ImplError("Source plugin '%s' does not implement stage()" % self.get_kind())
+        raise ImplError("Source plugin '{}' does not implement stage()".format(self.get_kind()))
 
     def init_workspace(self, directory):
         """Initialises a new workspace
diff --git a/buildstream/utils.py b/buildstream/utils.py
index f49e69fc7..57830f8a4 100644
--- a/buildstream/utils.py
+++ b/buildstream/utils.py
@@ -433,7 +433,7 @@ def get_host_tool(name):
     program_path = shutil.which(name, path=search_path)
 
     if not program_path:
-        raise ProgramNotFoundError("Did not find '%s' in PATH: %s" % (name, search_path))
+        raise ProgramNotFoundError("Did not find '{}' in PATH: {}".format(name, search_path))
 
     return program_path
 
@@ -500,7 +500,7 @@ def _copy_directories(srcdir, destdir, target):
                 yield (new_dir, mode)
             else:
                 raise OSError('Source directory tree has file where '
-                              'directory expected: %s' % dir)
+                              'directory expected: {}'.format(dir))
 
 
 def _ensure_real_directory(root, destpath):
@@ -515,8 +515,8 @@ def _ensure_real_directory(root, destpath):
     if not realpath.startswith(os.path.realpath(root)):
         raise IOError('Destination path resolves to a path outside ' +
                       'of the staging area\n\n' +
-                      '  Destination path: %s\n' % destpath +
-                      '  Real path: %s' % realpath)
+                      '  Destination path: {}\n'.format(destpath) +
+                      '  Real path: {}'.format(realpath))
 
     # Ensure the real destination path exists before trying to get the mode
     # of the real destination path.
@@ -592,8 +592,8 @@ def _process_list(srcdir, destdir, filelist, actionfunc, result, ignore_missing=
 
             dest_stat = os.lstat(os.path.realpath(destpath))
             if not stat.S_ISDIR(dest_stat.st_mode):
-                raise OSError('Destination not a directory. source has %s'
-                              ' destination has %s' % (srcpath, destpath))
+                raise OSError('Destination not a directory. source has {}'
+                              ' destination has {}'.format(srcpath, destpath))
             permissions.append((destpath, os.stat(srcpath).st_mode))
 
         elif stat.S_ISLNK(mode):
@@ -626,7 +626,7 @@ def _process_list(srcdir, destdir, filelist, actionfunc, result, ignore_missing=
 
         else:
             # Unsupported type.
-            raise OSError('Cannot extract %s into staging-area. Unsupported type.' % srcpath)
+            raise OSError('Cannot extract {} into staging-area. Unsupported type.'.format(srcpath))
 
     # Write directory permissions now that all files have been written
     for d, perms in permissions:
@@ -939,7 +939,7 @@ def _glob2re(pat):
                     stuff = '^' + stuff[1:]
                 elif stuff[0] == '^':
                     stuff = '\\' + stuff
-                res = '%s[%s]' % (res, stuff)
+                res = '{}[{}]'.format(res, stuff)
         else:
             res = res + re.escape(c)
     return res + '\Z(?ms)'
diff --git a/tests/project/data/plugins/elements/custom.py b/tests/project/data/plugins/elements/custom.py
index e27e859e5..c18c234a9 100644
--- a/tests/project/data/plugins/elements/custom.py
+++ b/tests/project/data/plugins/elements/custom.py
@@ -4,7 +4,7 @@ from buildstream import Element
 class CustomElement(Element):
 
     def configure(self, node):
-        print("Element Data: %s" % node)
+        print("Element Data: {}".format(node))
         self.node_validate(node, ['configuration'])
         self.configuration = self.node_subst_member(node, "configuration", '')
 
diff --git a/tests/project/data/plugins/sources/custom.py b/tests/project/data/plugins/sources/custom.py
index def1d3cd1..54c372bac 100644
--- a/tests/project/data/plugins/sources/custom.py
+++ b/tests/project/data/plugins/sources/custom.py
@@ -4,7 +4,7 @@ from buildstream import Source, Consistency
 class CustomSource(Source):
 
     def configure(self, node):
-        print("Source Data: %s" % node)
+        print("Source Data: {}".format(node))
         self.node_validate(node, ['configuration'] + Source.COMMON_CONFIG_KEYS)
         self.configuration = self.node_get_member(node, str, "configuration")
 
diff --git a/tests/variables/variables.py b/tests/variables/variables.py
index 7562857f9..0352ecd27 100644
--- a/tests/variables/variables.py
+++ b/tests/variables/variables.py
@@ -32,8 +32,8 @@ def assert_command(datafiles, tmpdir, target, command, expected):
     assert(commands.get(command) is not None)
     assert(len(commands[command]) > 0)
 
-    print("Commands:\n%s" % commands[command][0])
-    print("Expected:\n%s" % expected)
+    print("Commands:\n{}".format(commands[command][0]))
+    print("Expected:\n{}".format(expected))
 
     assert(commands[command][0] == expected)