Simply creating a grid element doesn't get you very far. You need to define the structure of the grid as well. To add some columns to the grid, use the <code>grid-template-columns</code> property on a grid container as demonstrated below:
The number of parameters given to the <code>grid-template-columns</code> property indicates the number of columns in the grid, and the value of each parameter indicates the width of each column.
testString: assert(code.match(/.container\s*?{[\s\S]*grid-template-columns\s*?:\s*?100px\s*?100px\s*?100px\s*?;[\s\S]*}/gi), '<code>container</code> class should have a <code>grid-template-columns</code> property with three units of <code>100px</code>.');