function getTestContext() {
    if (context === unknownContext || (context && context.isContextLost())) {
        var canvas = _pixi_settings__WEBPACK_IMPORTED_MODULE_0__.settings.ADAPTER.createCanvas();
        var gl = void 0;
        if (_pixi_settings__WEBPACK_IMPORTED_MODULE_0__.settings.PREFER_ENV >= _pixi_constants__WEBPACK_IMPORTED_MODULE_1__.ENV.WEBGL2) {
            gl = canvas.getContext('webgl2', {});
        }
        if (!gl) {
            gl = (canvas.getContext('webgl', {})
                || canvas.getContext('experimental-webgl', {}));
            if (!gl) {
                // fail, not able to get a context
                gl = null;
            }
            else {
                // for shader testing..
                gl.getExtension('WEBGL_draw_buffers');
            }
        }
        context = gl;
    }
    return context;
}
returns a little WebGL context to use for program inspection.
@static
@private
@returns {WebGLRenderingContext} a gl context to test with