clean up handling of silent

jupyterlab/tests/test_app.py

@@ -185,10 +185,6 @@ jest_flags['coverage'] = (
     {'JestApp': {'coverage': True}},
     'Run coverage'
 )
-jest_flags['silent'] = (
-    {'JestApp': {'silent': True}},
-    'Watch all test files'
-)
 jest_flags['watchAll'] = (
     {'JestApp': {'watchAll': True}},
     'Watch all test files'
@@ -204,8 +200,6 @@ class JestApp(ProcessTestApp):
 
     watchAll = Bool(False).tag(config=True)
 
-    silent = Bool(False).tag(config=True)
-
     aliases = jest_aliases
 
     flags = jest_flags
@@ -228,7 +222,7 @@ class JestApp(ProcessTestApp):
 
         cmd = []
         if self.coverage:
-            cmd += [jest, '--coverage']
+            cmd += [jest, '--coverage', '--silent']
         elif debug:
             cmd += ['node', '--inspect-brk', jest,  '--no-cache']
             if self.watchAll:
@@ -238,9 +232,6 @@ class JestApp(ProcessTestApp):
         else:
             cmd += [jest]
 
-        if self.silent:
-            cmd += ['--silent']
-
         if self.testPathPattern:
             cmd += ['--testPathPattern', self.testPathPattern]