Fix B904 (raise exceptions with `raise ... from ...`)

tests/test_build_epub.py

@@ -385,7 +385,7 @@ def test_run_epubcheck(app):
         except CalledProcessError as exc:
             print(exc.stdout.decode('utf-8'))
             print(exc.stderr.decode('utf-8'))
-            raise AssertionError('epubcheck exited with return code %s' % exc.returncode)
+            raise AssertionError(f'epubcheck exited with return code {exc.returncode}') from exc
 
 
 def test_xml_name_pattern_check():

tests/test_build_gettext.py

@@ -74,7 +74,7 @@ def test_msgfmt(app):
         except CalledProcessError as exc:
             print(exc.stdout)
             print(exc.stderr)
-            raise AssertionError('msginit exited with return code %s' % exc.returncode)
+            raise AssertionError(f'msginit exited with return code {exc.returncode}') from exc
 
         assert (app.outdir / 'en_US.po').is_file(), 'msginit failed'
         try:
@@ -86,7 +86,7 @@ def test_msgfmt(app):
         except CalledProcessError as exc:
             print(exc.stdout)
             print(exc.stderr)
-            raise AssertionError('msgfmt exited with return code %s' % exc.returncode)
+            raise AssertionError(f'msgfmt exited with return code {exc.returncode}') from exc
 
         mo = app.outdir / 'en' / 'LC_MESSAGES' / 'test_root.mo'
         assert mo.is_file(), 'msgfmt failed'

tests/test_build_latex.py

@@ -73,7 +73,7 @@ def compile_latex_document(app, filename='python.tex', docclass='manual'):
         print(exc.stdout.decode('utf8'))
         print(exc.stderr.decode('utf8'))
         raise AssertionError(f'{app.config.latex_engine} exited with '
-                             f'return code {exc.returncode}')
+                             f'return code {exc.returncode}') from exc
 
 
 def skip_if_requested(testfunc):

tests/test_build_texinfo.py

@@ -56,7 +56,7 @@ def test_texinfo(app, status, warning):
     except CalledProcessError as exc:
         print(exc.stdout)
         print(exc.stderr)
-        raise AssertionError('makeinfo exited with return code %s' % exc.retcode)
+        raise AssertionError(f'makeinfo exited with return code {exc.retcode}') from exc
 
 
 @pytest.mark.sphinx('texinfo', testroot='markup-rubric')