1cb93a386Sopenharmony_ciuniform half4 testInputs;  // equals (-1.25, 0, 0.75, 2.25)
2cb93a386Sopenharmony_ciuniform half4 colorGreen, colorRed;
3cb93a386Sopenharmony_ci
4cb93a386Sopenharmony_cihalf4 main(float2 coords) {
5cb93a386Sopenharmony_ci    half4 expected = half4(0);  // derivative of a constant is zero
6cb93a386Sopenharmony_ci    return (dFdy(testInputs.x)    == expected.x     &&
7cb93a386Sopenharmony_ci            dFdy(testInputs.xy)   == expected.xy    &&
8cb93a386Sopenharmony_ci            dFdy(testInputs.xyz)  == expected.xyz   &&
9cb93a386Sopenharmony_ci            dFdy(testInputs.xyzw) == expected.xyzw  &&
10cb93a386Sopenharmony_ci            sign(dFdy(coords.xx)) == half2(0, 0)    &&
11cb93a386Sopenharmony_ci            sign(dFdy(coords.yy)) == half2(1, 1)    &&
12cb93a386Sopenharmony_ci            sign(dFdy(coords.xy)) == half2(0, 1)) ? colorGreen : colorRed;
13cb93a386Sopenharmony_ci}
14