Indeed,

Appears that the pixel_size is a "double" for the example tests, but the random tests are 2 integers separated by a space... Does not appear to be solvable at the moment. The space appears to be in error going by the test comment.

[1] "Testing for wall_length = 7731, pixel_size = 715"
[1] 7731
[1]  7 15
[1] "integer"

R tests are fine, not a kata issue. Read the description again.