Method StartSession

dotnet/src/webdriver/WebDriver.cs:592–666

Starts a session with the driver Capabilities of the browser

(ICapabilities capabilities)

    /// </summary>
    /// <param name="capabilities">Capabilities of the browser</param>
    [MemberNotNull(nameof(SessionId))]
    [MemberNotNull(nameof(Capabilities))]
    protected void StartSession(ICapabilities capabilities)
    {
        Dictionary<string, object?> parameters = new Dictionary<string, object?>();

        // If the object passed into the RemoteWebDriver constructor is a
        // RemoteSessionSettings object, it is expected that all intermediate
        // and end nodes are compliant with the W3C WebDriver Specification,
        // and therefore will already contain all of the appropriate values
        // for establishing a session.
        if (capabilities is not RemoteSessionSettings remoteSettings)
        {
            Dictionary<string, object> matchCapabilities = this.GetCapabilitiesDictionary(capabilities);

            if (this.CommandExecutor is Remote.HttpCommandExecutor httpExecutor)
            {
                matchCapabilities["se:remoteUrl"] = httpExecutor.RemoteServerUri.AbsoluteUri;
            }

            List<object> firstMatchCapabilitiesList = new List<object>();
            firstMatchCapabilitiesList.Add(matchCapabilities);

            Dictionary<string, object> specCompliantCapabilitiesDictionary = new Dictionary<string, object>();
            specCompliantCapabilitiesDictionary["firstMatch"] = firstMatchCapabilitiesList;

            parameters.Add("capabilities", specCompliantCapabilitiesDictionary);
        }
        else
        {
            Dictionary<string, object?> remoteSettingsDictionary = remoteSettings.ToDictionary();

            // Advertise se:remoteUrl on the caller's behalf, as every other binding does. It must be
            // nested in alwaysMatch (the Grid drops top-level metadata), built into a fresh copy so
            // the caller-owned RemoteSessionSettings is not mutated. Only a matched capability counts
            // as explicit here: a se:remoteUrl set via AddMetadataSetting stays top-level, is ignored
            // by the Grid, and does not suppress this injection (the executor URL stays authoritative).
            // Skip only when se:remoteUrl already lives in alwaysMatch/firstMatch, to preserve that
            // value and avoid an alwaysMatch/firstMatch overlap. If only one of several firstMatch
            // alternatives sets it explicitly, injection is suppressed for all of them; that
            // multi-alternative case is intentionally not supported.
            if (this.CommandExecutor is Remote.HttpCommandExecutor remoteHttpExecutor
                && !ContainsMatchCapability(remoteSettingsDictionary, "se:remoteUrl"))
            {
                Dictionary<string, object?> alwaysMatch = new Dictionary<string, object?>();
                if (remoteSettingsDictionary.TryGetValue("alwaysMatch", out object? existingAlwaysMatch)
                    && existingAlwaysMatch is IDictionary<string, object> existingCapabilities)
                {
                    foreach (KeyValuePair<string, object> capability in existingCapabilities)
                    {
                        alwaysMatch[capability.Key] = capability.Value;
                    }
                }

                alwaysMatch["se:remoteUrl"] = remoteHttpExecutor.RemoteServerUri.AbsoluteUri;
                remoteSettingsDictionary["alwaysMatch"] = alwaysMatch;
            }