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Merged
josevalim merged 2 commits into from
Apr 9, 2021
Merged

Fixing bug in Enum.dedup/1 #10886

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ac7e74c
Fixing bug in Enum.dedup/1
sabiwara Apr 8, 2021
efdfd6b
Test dedup/1 with stream
sabiwara Apr 8, 2021
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2 changes: 1 addition & 1 deletion lib/elixir/lib/enum.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -787,7 +787,7 @@ defmodule Enum do
def dedup(enumerable) do
Enum.reduce(enumerable, [], fn x, acc ->
case acc do
[^x, _] -> acc
[^x | _] -> acc
_ -> [x | acc]
end
end)
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12 changes: 12 additions & 0 deletions lib/elixir/test/elixir/enum_test.exs
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Expand Up @@ -184,6 +184,18 @@ defmodule EnumTest do
assert Enum.dedup([nil]) == [nil]
end

test "dedup/1 with streams" do
dedup_stream = fn list -> list |> Stream.map(& &1) |> Enum.dedup() end

assert dedup_stream.([1, 1, 2, 1, 1, 2, 1]) == [1, 2, 1, 2, 1]
assert dedup_stream.([2, 1, 1, 2, 1]) == [2, 1, 2, 1]
assert dedup_stream.([1, 2, 3, 4]) == [1, 2, 3, 4]
assert dedup_stream.([1, 1.0, 2.0, 2]) == [1, 1.0, 2.0, 2]
assert dedup_stream.([]) == []
assert dedup_stream.([nil, nil, true, {:value, true}]) == [nil, true, {:value, true}]
assert dedup_stream.([nil]) == [nil]
end

test "dedup_by/2" do
assert Enum.dedup_by([{1, :x}, {2, :y}, {2, :z}, {1, :x}], fn {x, _} -> x end) ==
[{1, :x}, {2, :y}, {1, :x}]
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