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| author | Paul Eggert <eggert@cs.ucla.edu> | 2019-08-16 16:25:02 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2019-08-16 16:27:27 -0700 |
| commit | f9fd12a30b3d94eb48f7b309907d136d7b2682ac (patch) | |
| tree | d00aa93beec6eb1013127ee251342f39f135a994 /test | |
| parent | e82923c817159c751aa9c902093a46b9457e8499 (diff) | |
| download | emacs-f9fd12a30b3d94eb48f7b309907d136d7b2682ac.tar.gz | |
Fix time-add rounding bug
Without this fix, time arithmetic yielded results that were not
mathematically accurate, even though the exact results were
representable; for example, (time-add 0 1e-13) yielded a timestamp
equal to 0 instead of to 1e-13.
* lisp/timezone.el (timezone-time-from-absolute):
Let time-add do its thing rather than using floating point
internally, which has rounding errors. We now have bignums and so
don’t need floating point to avoid overflow issues.
* src/timefns.c (timeform_sub_ps_p): New function.
(time_arith): If either argument is a float, represent the
result exactly instead of discarding sub-ps info.
* test/lisp/timezone-tests.el (timezone-tests-time-from-absolute):
Don’t assume (HI LO US PS) timestamp format.
* test/src/emacs-module-tests.el (mod-test-add-nanosecond/valid):
Don’t assume that time-add discards sub-ns info.
* test/src/timefns-tests.el (time-rounding-tests):
Add regression test to detect time-add rounding bug.
Diffstat (limited to 'test')
| -rw-r--r-- | test/lisp/timezone-tests.el | 7 | ||||
| -rw-r--r-- | test/src/emacs-module-tests.el | 7 | ||||
| -rw-r--r-- | test/src/timefns-tests.el | 3 |
3 files changed, 12 insertions, 5 deletions
diff --git a/test/lisp/timezone-tests.el b/test/lisp/timezone-tests.el index 4b5f5617ecd..c374042fa5d 100644 --- a/test/lisp/timezone-tests.el +++ b/test/lisp/timezone-tests.el @@ -135,9 +135,10 @@ (should (equal (timezone-zone-to-minute "*invalid*") 0))) (ert-deftest timezone-tests-time-from-absolute () - (should (equal (timezone-time-from-absolute (* 2020 365) ; Jan 1 2020 - (* 12 60 60)) ; 12:00 - '(23911 48704 0 0)))) + (should (time-equal-p + (timezone-time-from-absolute (* 2020 365) ; Jan 1 2020 + (* 12 60 60)) ; 12:00 + '(23911 48704 0 0)))) ;; TODO: Write tests for timezone-tests-time-zone-from-absolute, which is a ;; bit tricky since the results depend on `current-time-zone'. diff --git a/test/src/emacs-module-tests.el b/test/src/emacs-module-tests.el index c44c386d30b..c5107847318 100644 --- a/test/src/emacs-module-tests.el +++ b/test/src/emacs-module-tests.el @@ -335,12 +335,15 @@ Interactively, you can try hitting \\[keyboard-quit] to quit." ;; New (TICKS . HZ) format. '(123456789 . 1000000000))) (ert-info ((format "input: %s" input)) - (let ((result (mod-test-add-nanosecond input))) + (let ((result (mod-test-add-nanosecond input)) + (desired-result + (let ((hz 1000000000)) + (time-add (time-convert input hz) (cons 1 hz))))) (should (consp result)) (should (integerp (car result))) (should (integerp (cdr result))) (should (cl-plusp (cdr result))) - (should (time-equal-p result (time-add input '(0 0 0 1000)))))))) + (should (time-equal-p result desired-result)))))) (ert-deftest mod-test-add-nanosecond/nil () (should (<= (float-time (mod-test-add-nanosecond nil)) diff --git a/test/src/timefns-tests.el b/test/src/timefns-tests.el index 1b1032deaa1..362e7655a91 100644 --- a/test/src/timefns-tests.el +++ b/test/src/timefns-tests.el @@ -145,6 +145,9 @@ (< 0.99 (/ (- (float-time a)) (float-time b)) 1.01)))))))) +(ert-deftest time-rounding-tests () + (should (time-equal-p 1e-13 (time-add 0 1e-13)))) + (ert-deftest encode-time-dst-numeric-zone () "Check for Bug#35502." (should (time-equal-p |