Improve diff table output

[emiltin]

Issue

Improves cucumber diff table output, by showing which cells was wrong: Instead of showing (-) and (+) in all columns, only show it in the columns with wrong results.

Before:

     Tables were not identical:
     |     highway |     junction   |     oneway |     oneway:bicycle |     forw |     backw |
     |     primary |                |     yes    |     yes            |     x    |           |
     | (-) primary | (-)            | (-) yes    | (-) no             | (-)      | (-) x     |
     | (+) primary | (+)            | (+) yes    | (+) no             | (+) x    | (+)       |
     |     primary |                |     yes    |     -1             |     x    |           |
     |     primary |                |     no     |     yes            |     x    |     x     |
     |     primary |                |     no     |     no             |     x    |     x     |
     |     primary |                |     no     |     -1             |     x    |     x     |
     | (-) primary | (-)            | (-) -1     | (-) yes            | (-)      | (-)       |
     | (+) primary | (+)            | (+) -1     | (+) yes            | (+)      | (+) x     |
     |     primary |                |     -1     |     no             |          |     x     |
     |     primary |                |     -1     |     -1             |          |     x     |
     |     primary |     roundabout |            |     yes            |     x    |           |
     | (-) primary | (-) roundabout | (-)        | (-) no             | (-) x    | (-) x     |
     | (+) primary | (+) roundabout | (+)        | (+) no             | (+) x    | (+)       |
     |     primary |     roundabout |            |     -1             |     x    |           |

After:

     Tables were not identical:
     | highway | junction   | oneway | oneway:bicycle |     forw |     backw |
     | primary |            | yes    | yes            |     x    |           |
     | primary |            | yes    | no             | (-)      | (-) x     |
     | primary |            | yes    | no             | (+) x    | (+)       |
     | primary |            | yes    | -1             |     x    |           |
     | primary |            | no     | yes            |     x    |     x     |
     | primary |            | no     | no             |     x    |     x     |
     | primary |            | no     | -1             |     x    |     x     |
     | primary |            | -1     | yes            |          | (-)       |
     | primary |            | -1     | yes            |          | (+) x     |
     | primary |            | -1     | no             |          |     x     |
     | primary |            | -1     | -1             |          |     x     |
     | primary | roundabout |        | yes            |     x    |           |
     | primary | roundabout |        | no             |     x    | (-) x     |
     | primary | roundabout |        | no             |     x    | (+)       |
     | primary | roundabout |        | -1             |     x    |           |

The colors can't be seen in the text above, but is unchanged, except I changed the color of the headers to gray.

[daniel-j-h]

Sweet!

Just asking here out of interest, but is this related to cucumber/cucumber-js#534 not being implemented upstream - and if so should these changes be made to cucumber-js instead?

[TheMarex]

Yes this should live upstream eventually, but for that our whole diff code would need to be ported. Not sure how much effort that would be.