l[pname], ext.MIRROR_CLAMP_TO_EDGE_EXT);
        wtu.glErrorShouldBe(gl, gl.NO_ERROR, "should be no errors from samplerParameterf");
        shouldBe(`gl.getSamplerParameter(sampler, gl.${pname})`, "ext.MIRROR_CLAMP_TO_EDGE_EXT");
        gl.samplerParameterf(sampler, gl[pname], gl.REPEAT);
    }
}

function checkSampling() {
    debug("");
    debug(`Check texture sampling with mirror-clamp-to-edge mode`);

    wtu.setupUnitQuad(gl);
    const vs = `precision highp float;
        attribute vec4 vPosition;
