build: fix linter error (see full commit message)

"Unexpected use of Mocha `beforeEach` hook for a single test case"
"Unexpected use of Mocha `afterEach` hook for a single test case"

Author: gildas2k

test/server/talk-control-server.spec.js

@@ -30,16 +30,8 @@ describe('should have instantiated', function() {
     });
 
     describe('emitStateChanges()', function() {
-        let emit;
-        beforeEach(function() {
-            emit = stub(talkControlServer.eventBusServer, 'emit');
-        });
-
-        afterEach(function() {
-            emit.restore();
-        });
-
         it('should fire "gotoSlide" event', function() {
+            const emit = stub(talkControlServer.eventBusServer, 'emit');
             // Given
             const state = { currentSlide: { h: 1, v: 0, f: 0 }, slides: [{ h: 0, v: 0, f: 0, fMax: 0 }, { h: 1, v: 0, f: 0, fMax: 0 }] };
             stub(store, 'getState').returns(state);