strain

elixir/strain/test/strain_test.exs

@@ -0,0 +1,107 @@
+defmodule StrainTest do
+  use ExUnit.Case
+
+  defp is_odd?(n), do: rem(n, 2) == 1
+  defp is_even?(n), do: rem(n, 2) == 0
+
+  describe "keep" do
+    # @tag :pending
+    test "on empty list returns empty list" do
+      assert Strain.keep([], fn _ -> true end) == []
+    end
+
+    # @tag :pending
+    test "keep everything" do
+      assert Strain.keep([1, 3, 5], fn _ -> true end) == [1, 3, 5]
+    end
+
+    # @tag :pending
+    test "keep nothing" do
+      assert Strain.keep([1, 3, 5], fn _ -> false end) == []
+    end
+
+    # @tag :pending
+    test "keep first and last" do
+      assert Strain.keep([1, 2, 3], &is_odd?/1) == [1, 3]
+    end
+
+    # @tag :pending
+    test "keep neither first nor last" do
+      assert Strain.keep([1, 2, 3], &is_even?/1) == [2]
+    end
+
+    # @tag :pending
+    test "keep strings" do
+      words = ~w(apple zebra banana zombies cherimoya zelot)
+      assert Strain.keep(words, &String.starts_with?(&1, "z")) == ~w(zebra zombies zelot)
+    end
+
+    # @tag :pending
+    test "keep lists" do
+      rows = [
+        [1, 2, 3],
+        [5, 5, 5],
+        [5, 1, 2],
+        [2, 1, 2],
+        [1, 5, 2],
+        [2, 2, 1],
+        [1, 2, 5]
+      ]
+
+      assert Strain.keep(rows, fn row -> 5 in row end) == [
+               [5, 5, 5],
+               [5, 1, 2],
+               [1, 5, 2],
+               [1, 2, 5]
+             ]
+    end
+  end
+
+  describe "discard" do
+    # @tag :pending
+    test "on empty list returns empty list" do
+      assert Strain.discard([], fn _ -> true end) == []
+    end
+
+    # @tag :pending
+    test "discard everything" do
+      assert Strain.discard([1, 3, 5], fn _ -> true end) == []
+    end
+
+    # @tag :pending
+    test "discard nothing" do
+      assert Strain.discard([1, 3, 5], fn _ -> false end) == [1, 3, 5]
+    end
+
+    # @tag :pending
+    test "discard first and last" do
+      assert Strain.discard([1, 2, 3], &is_odd?/1) == [2]
+    end
+
+    # @tag :pending
+    test "discard neither first nor last" do
+      assert Strain.discard([1, 2, 3], &is_even?/1) == [1, 3]
+    end
+
+    # @tag :pending
+    test "discard strings" do
+      words = ~w(apple zebra banana zombies cherimoya zelot)
+      assert Strain.discard(words, &String.starts_with?(&1, "z")) == ~w(apple banana cherimoya)
+    end
+
+    # @tag :pending
+    test "discard arrays" do
+      rows = [
+        [1, 2, 3],
+        [5, 5, 5],
+        [5, 1, 2],
+        [2, 1, 2],
+        [1, 5, 2],
+        [2, 2, 1],
+        [1, 2, 5]
+      ]
+
+      assert Strain.discard(rows, fn row -> 5 in row end) == [[1, 2, 3], [2, 1, 2], [2, 2, 1]]
+    end
+  end
+end

elixir/strain/test/test_helper.exs

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+ExUnit.start()
+ExUnit.configure(exclude: :pending, trace: true)