Long double tests are too strict on platforms without long double

[DavisVaughan]

They are barely off. On these platforms long double is aliased to double, so in theory I think the results should be identical. I think the difference comes from the fact that the elements are probably being added in different orders (base R adds in sequential order, slider adds in an order defined from the segment tree), and precision loss aggregates in slightly different ways.

M1Mac CRAN failure:

  Running ‘testthat.R’
 ERROR
Running the tests in ‘tests/testthat.R’ failed.
Complete output:
  > library(testthat)
  > library(slider)
  > 
  > test_check("slider")
  ══ Skipped tests ═══════════════════════════════════════════════════════════════
  ● On CRAN (13)
  
  ══ Failed tests ════════════════════════════════════════════════════════════════
  ── Failure (test-summary-slide.R:247:3): precision matches base R (long doubles) ──
  mean(x) (`actual`) not identical to slide_mean(x, before = Inf)[[length(x)]] (`expected`).
  
    `actual`: 0.20634920634920634
  `expected`: 0.20634920634920637
  
  [ FAIL 1 | WARN 0 | SKIP 13 | PASS 1073 ]
  Error: Test failures
  Execution halted
* checking for unstated dependencies in vignettes ... OK
* checking package vignettes in ‘inst/doc’ ... OK
* checking re-building of vignette outputs ... OK
* checking PDF version of manual ... OK
* checking for detritus in the temp directory ... OK
* DONE

Status: 1 ERROR
See
  ‘/Users/ripley/R/packages/tests-devel/slider.Rcheck/00check.log’
for details.

       41.76 real        29.94 user         5.05 sys

noLD CRAN failure:

  Running ‘testthat.R’ [26s/28s]
 [26s/29s] ERROR
Running the tests in ‘tests/testthat.R’ failed.
Complete output:
  > library(testthat)
  > library(slider)
  > 
  > test_check("slider")
  ══ Skipped tests ═══════════════════════════════════════════════════════════════
  ● On CRAN (13)
  
  ══ Failed tests ════════════════════════════════════════════════════════════════
  ── Failure (test-summary-slide.R:76:3): precision matches base R (long doubles) ──
  sum(x) (`actual`) not identical to slide_sum(x, before = Inf)[[length(x)]] (`expected`).
  
    `actual`: 1.4285714285714282
  `expected`: 1.4285714285714284
  
  [ FAIL 1 | WARN 0 | SKIP 13 | PASS 1073 ]
  Error: Test failures
  Execution halted
* checking for unstated dependencies in vignettes ... OK
* checking package vignettes in ‘inst/doc’ ... OK
* checking re-building of vignette outputs ... [10s/12s] OK
* checking PDF version of manual ... OK
* checking for non-standard things in the check directory ... OK
* checking for detritus in the temp directory ... OK
* DONE

Status: 1 ERROR
See
  ‘/data/gannet/ripley/R/packages/tests-noLD/slider.Rcheck/00check.log’
for details.

Command exited with non-zero status 1
Time 2:04.86, 87.44 + 7.76