proxyPacFile = "file:///" + proxyPacFile;

Proxy proxyPAC = new Proxy();
proxyPAC.setProxyAutoconfigUrl(proxyPacFile);
proxyPAC.setProxyType(ProxyType.PAC);

capabilities = DesiredCapabilities.internetExplorer();
capabilities.setCapability(InternetExplorerDriver.INTRODUCE_FLAKINESS_BY_IGNORING_SECURITY_DOMAINS, true);
capabilities.setCapability(InternetExplorerDriver.IE_USE_PRE_PROCESS_PROXY, true);
capabilities.setCapability(CapabilityType.PROXY, proxyPAC);

case CHROME:
        capabilities = DesiredCapabilities.chrome();
        capabilities.setCapability(CapabilityType.PROXY, proxyPAC);
        break;

    case FIREFOX:
        capabilities = DesiredCapabilities.firefox();

        FirefoxProfile profile = new FirefoxProfile();
        profile.setPreference("network.proxy.type", 2);
        capabilities.setCapability(FirefoxDriver.PROFILE, profile);

        capabilities.setCapability(CapabilityType.PROXY, proxyPAC);
        break;