added docs and test for issue JuliaLang#18090 (JuliaLang#20209)

base/associative.jl

@@ -64,9 +64,11 @@ in(k, v::KeyIterator) = get(v.dict, k, secret_table_token) !== secret_table_toke
     keys(a::Associative)
 
 Return an iterator over all keys in a collection.
-`collect(keys(d))` returns an array of keys.
+`collect(keys(a))` returns an array of keys.
 Since the keys are stored internally in a hash table,
 the order in which they are returned may vary.
+But `keys(a)` and `values(a)` both iterate `a` and
+return the elements in the same order.
 
 ```jldoctest
 julia> a = Dict('a'=>2, 'b'=>3)
@@ -87,7 +89,11 @@ eachindex(a::Associative) = KeyIterator(a)
     values(a::Associative)
 
 Return an iterator over all values in a collection.
-`collect(values(d))` returns an array of values.
+`collect(values(a))` returns an array of values.
+Since the values are stored internally in a hash table,
+the order in which they are returned may vary.
+But `keys(a)` and `values(a)` both iterate `a` and
+return the elements in the same order.
 
 ```jldoctest
 julia> a = Dict('a'=>2, 'b'=>3)

test/dict.jl

@@ -673,3 +673,12 @@ end
 @testset "issue #19179 throwing error in dict constructor" begin
     @test_throws Error19179 Dict(i => throw(Error19179()) for i in 1:10)
 end
+
+# issue #18090
+let
+    d = Dict(i => i^2 for i in 1:10_000)
+    z = zip(keys(d), values(d))
+    for (pair, tupl) in zip(d, z)
+        @test pair[1] == tupl[1] && pair[2] == tupl[2]
+    end
+end