uniform half4 testInputs;  // equals (-1.25, 0, 0.75, 2.25)
uniform half4 colorGreen, colorRed;

half4 main(float2 coords) {
    const half4 constVal = half4(-1.25, 0, 0.75, 2.25);
    half4 expected = half4(1.25, 0, 0.75, 2.25);
    return (abs(testInputs.x)    == expected.x     &&
            abs(testInputs.xy)   == expected.xy    &&
            abs(testInputs.xyz)  == expected.xyz   &&
            abs(testInputs.xyzw) == expected.xyzw  &&
            abs(constVal.x)      == expected.x     &&
            abs(constVal.xy)     == expected.xy    &&
            abs(constVal.xyz)    == expected.xyz   &&
            abs(constVal.xyzw)   == expected.xyzw) ? colorGreen : colorRed;
}