Check zero case and fix bug thus revealed

Author: hadley

R/expect-comparison.R

@@ -42,7 +42,11 @@ expect_compare_ <- function(
     abort("Result of comparison must be a single logical value")
   }
   if (!isTRUE(cmp)) {
-    digits <- min_digits(act$val, exp$val)
+    digits <- max(
+      digits(act$val),
+      digits(exp$val),
+      min_digits(act$val, exp$val)
+    )
     msg <- sprintf(
       "%s is %s %s.\n%s - %s = %s %s 0",
       act$lab,

tests/testthat/_snaps/expect-comparison.md

@@ -8,3 +8,8 @@
     `x` is not strictly greater than 1.1 * x.
     0.0000100 - 0.0000110 = -0.0000010 <= 0
 
+---
+
+    `x` is not strictly less than `x`.
+    100.0 - 100.0 = 0.0 >= 0
+

tests/testthat/test-expect-comparison.R

@@ -12,6 +12,9 @@ test_that("useful output when numbers are very small", {
   x <- 1e-5
   expect_snapshot_failure(expect_lte(1.1 * x, x))
   expect_snapshot_failure(expect_gt(x, 1.1 * x))
+
+  x <- 100
+  expect_snapshot_failure(expect_lt(x, x))
 })
 
 test_that("comparison result object invisibly", {