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 (dFdx(testInputs.x)      == expected.x     &&
7cb93a386Sopenharmony_ci            dFdx(testInputs.xy)     == expected.xy    &&
8cb93a386Sopenharmony_ci            dFdx(testInputs.xyz)    == expected.xyz   &&
9cb93a386Sopenharmony_ci            dFdx(testInputs.xyzw)   == expected.xyzw  &&
10cb93a386Sopenharmony_ci            sign(fwidth(coords.xx)) == half2(1, 1)        &&
11cb93a386Sopenharmony_ci            sign(fwidth(coords.x1)) == half2(1, 0)        &&
12cb93a386Sopenharmony_ci            sign(fwidth(coords.yy)) == half2(1, 1)        &&
13cb93a386Sopenharmony_ci            sign(fwidth(coords.0y)) == half2(0, 1)        &&
14cb93a386Sopenharmony_ci            sign(fwidth(coords.xy)) == half2(1, 1)) ? colorGreen : colorRed;
15cb93a386Sopenharmony_ci}
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