Avoid rare NaN in calc_check_iterations (#210)

* avoid NaN in calc_check_iterations

* add test for #209

* fix test

* more fix

src/ProgressMeter.jl

@@ -244,6 +244,11 @@ running_ijulia_kernel() = isdefined(Main, :IJulia) && Main.IJulia.inited
 clear_ijulia() = (IJULIABEHAVIOR[] != IJuliaAppend) && running_ijulia_kernel()
 
 function calc_check_iterations(p, t)
+    if t == p.tlast
+        # avoid a NaN which could happen because the print time compensation makes an assumption about how long printing
+        # takes, therefore it's possible (but rare) for `t == p.tlast`
+        return p.check_iterations
+    end
     # Adjust the number of iterations that skips time check based on how accurate the last number was
     iterations_per_dt = (p.check_iterations / (t - p.tlast)) * p.dt
     return round(Int, clamp(iterations_per_dt, 1, p.check_iterations * 10))

test/core.jl

@@ -50,3 +50,11 @@ if get(ENV, "GITHUB_ACTIONS", "false") != "true" # CI environment is too unrelia
     @time noprog_perf(10^7)
     @test @elapsed(prog_perf(10^7)) < 9*@elapsed(noprog_perf(10^7))
 end
+
+# Avoid a NaN due to the estimated print time compensation
+# https://github.com/timholy/ProgressMeter.jl/issues/209
+prog = Progress(10)
+prog.check_iterations = 999
+t = time()
+prog.tlast = t
+@test ProgressMeter.calc_check_iterations(prog, t) == 999