Added tests for Stateful fix JuliaLang#30643

test/iterators.jl

@@ -623,3 +623,26 @@ end
     @test @inferred(first(z)) == (1, "a", 1.0, 1, "a", 1.0, 1, "a", 1.0)
     @test @inferred(first(Iterators.drop(z, 1))) == (2, "b", 2.0, 2, "a", 1.2, 1, "c", 1.0)
 end
+
+@testset "Stateful fix #30643" begin
+    @test Base.IteratorSize(1:10) isa Base.HasShape
+    a = Iterators.Stateful(1:10)
+    @test Base.IteratorSize(a) isa Base.HasLength
+    @test length(a) == 10
+    @test length(collect(a)) == 10
+    @test length(a) == 0
+    b = Iterators.Stateful(Iterators.take(1:10,3))
+    @test Base.IteratorSize(b) isa Base.HasLength
+    @test length(b) == 3
+    @test length(collect(b)) == 3
+    @test length(b) == 0
+    c = Iterators.Stateful(Iterators.countfrom(1))
+    @test Base.IteratorSize(c) isa Base.IsInfinite
+    @test length(Iterators.take(c,3)) == 3
+    @test length(collect(Iterators.take(c,3))) == 3
+    d = Iterators.Stateful(Iterators.filter(isodd,1:10))
+    @test Base.IteratorSize(d) isa Base.SizeUnknown
+    @test length(collect(Iterators.take(d,3))) == 3
+    @test length(collect(d)) == 2
+    @test length(collect(d)) == 0
+end