[GHC] #14711: Machine readable output of coverage

[GHC]

#14711: Machine readable output of coverage
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           Reporter:  Koterpillar    |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Code Coverage  |           Version:  8.2.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 When integrating with a CI system, it might be useful to fail the build,
 alert or take other actions based on coverage percentage. To do that, hpc
 needs to output a summary coverage report in a machine readable format.

 For example, the current output:

 {{{
  38% expressions used (1779/4624)
  57% boolean coverage (16/28)
       56% guards (9/16), 6 always True, 1 always False
       58% 'if' conditions (7/12), 2 always False, 3 unevaluated
      100% qualifiers (0/0)
   7% alternatives used (103/1410)
  75% local declarations used (102/136)
  40% top-level declarations used (185/457)
 }}}

 can be represented as:

 {{{
 {
   expressions: { total: 4624, used: 1779, percentage: 0.38 },
   boolean: { total: 28, used: 16, percentage: 0.57 },
   <...>
 }
 }}}

 This output can be then parsed to decide whether to fail the build,
 produce a coverage graph over time, etc.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14711>
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