I’m stuck with the d3 heatmap project i have the y-axis with the months as i’m requested, it looks like everything is fine! and is aligned but still don’t passes the test, in the code i’m using a timeScale() instead of a linearScale or a bandScale as i saw in another posts, anybody can help me? 
Here’s my code:
You’re right, everything passes the eye test. Your cells are hanging below the month ticks, so maybe you could keep things as they are and try to align the cells vertically centered on the ticks (so move them up one-half the cell height), or try having the bottoms of the cells aligned with the ticks.
I do remember trying several scales and settled on a band scale to get everything to work. If I remember the lessons correctly, D3 draws with an x-axis like normal Cartesian coordinates, but the y-axis is opposite normal Cartesian coordinates. So if D3 is drawing from the bottom up on your cells, it’s clear the y-values won’t align with the y-axis ticks.
Short of looking at the source for this particular test, I’m not sure what else to try.
Thank you very much for your feedback @jeremy.a.gray , i will try to apply your advices, and i tell you if it works! 
THAAAAAANK YOUUUUUUUUUUUUUU!!! You cannot understand how mad i was because of this! I’ve spent a lot of time trying to figure out where the bug was! I was never gonna think that the problem was with the centering of the cells! Oh my God you’re a genius! Thank you! I really appreciate your help! 