Test that functions returning strings really do return strings (and not e.g. null) On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS gl.getShaderSource(vs) returns a string PASS gl.getShaderInfoLog(vs) returns a string PASS gl.getShaderSource(vs) returns a string PASS gl.getShaderInfoLog(vs) returns a string PASS gl.getShaderSource(fs) returns a string PASS gl.getShaderInfoLog(fs) returns a string PASS gl.getShaderSource(fs) returns a string PASS gl.getShaderInfoLog(fs) returns a string PASS gl.getProgramInfoLog(prog) returns a string PASS gl.getProgramInfoLog(prog) returns a string PASS getSupportedExtensions() returns an array of strings PASS gl.getParameter(gl.VENDOR) returns a string PASS gl.getParameter(gl.RENDERER) returns a string PASS gl.getParameter(gl.VERSION) returns a string PASS gl.getParameter(gl.SHADING_LANGUAGE_VERSION) returns a string PASS successfullyParsed is true TEST COMPLETE