#19 -- Record information on multiple expectation failure an include in report

[gregmuellegger]

This is a proposed fix for #19

It records all failing expectations and prints those during reporting.

Here is a working example:

devtools::install_github("gregmuellegger/r-hedgehog", ref = "19-fix-expect-failure-reporting")

library(testthat)
library(hedgehog)

test_that("Demo: shows all failing expectations now", {
    forall(
        gen.element(1:10),
        function (n) {
            expect_equal(n, n + 1)
            expect_equal(n, n + 2)
            
            expect_equal(n, n)
        }
    )
})

output:

── Failure: Demo: shows all failing expectations now ───────────────────────────
Falsifiable after 1 tests, and 1 shrinks

<expectation_failure/expectation/error/condition>
`n` not equal to n + 1.
1/1 mismatches
[1] 1 - 2 == -1
Backtrace:
     ▆
  1. └─hedgehog::forall(...)
  2.   └─hedgehog:::run.prop(property, counterexample$smallest, curry)
  3.     ├─base::tryCatch(...)
  4.     │ └─base (local) tryCatchList(expr, classes, parentenv, handlers)
  5.     │   └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
  6.     │     └─base (local) doTryCatch(return(expr), name, parentenv, handler)
  7.     ├─base::withCallingHandlers(...)
  8.     ├─base::do.call(property, arguments)
  9.     └─`<fn>`(1L)
 10.       └─testthat::expect_equal(n, n + 1)

<expectation_failure/expectation/error/condition>
`n` not equal to n + 2.
1/1 mismatches
[1] 1 - 3 == -2
Backtrace:
     ▆
  1. └─hedgehog::forall(...)
  2.   └─hedgehog:::run.prop(property, counterexample$smallest, curry)
  3.     ├─base::tryCatch(...)
  4.     │ └─base (local) tryCatchList(expr, classes, parentenv, handlers)
  5.     │   └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
  6.     │     └─base (local) doTryCatch(return(expr), name, parentenv, handler)
  7.     ├─base::withCallingHandlers(...)
  8.     ├─base::do.call(property, arguments)
  9.     └─`<fn>`(1L)
 10.       └─testthat::expect_equal(n, n + 2)

Counterexample:
[1] 1

[HuwCampbell]

I'll have a good look at this as soon as I get chance.

Looks mostly right, but the output is a bit different to what it would be as just a testhat expectation (multiple stack traces).

I'm not using R a lot these days, but I'm happy to shepherd this and help where I can.