feat(utils): add str_occurence method

Author: mydearxym

lib/helper/utils.ex

@@ -237,4 +237,13 @@ defmodule Helper.Utils do
   defp update_word_count(word, acc) do
     Map.update(acc, to_string(word), 1, &(&1 + 1))
   end
+
+  # see https://stackoverflow.com/a/49558074/4050784
+  @spec str_occurence(String.t(), String.t()) :: Integer.t()
+  def str_occurence(string, substr) when is_binary(string) and is_binary(substr) do
+    len = string |> String.split(substr) |> length()
+    len - 1
+  end
+
+  def str_occurence(_, _), do: "must be strings"
 end

test/helper/utils_test.exs

@@ -91,34 +91,41 @@ defmodule GroupherServer.Test.Helper.UtilsTest do
   end
 
   describe "[deep merge]" do
-    test 'one level of maps without conflict' do
+    test "one level of maps without conflict" do
       result = Utils.deep_merge(%{a: 1}, %{b: 2})
       assert result == %{a: 1, b: 2}
     end
 
-    test 'two levels of maps without conflict' do
+    test "two levels of maps without conflict" do
       result = Utils.deep_merge(%{a: %{b: 1}}, %{a: %{c: 3}})
       assert result == %{a: %{b: 1, c: 3}}
     end
 
-    test 'three levels of maps without conflict' do
+    test "three levels of maps without conflict" do
       result = Utils.deep_merge(%{a: %{b: %{c: 1}}}, %{a: %{b: %{d: 2}}})
       assert result == %{a: %{b: %{c: 1, d: 2}}}
     end
 
-    test 'non-map value in left' do
+    test "non-map value in left" do
       result = Utils.deep_merge(%{a: 1}, %{a: %{b: 2}})
       assert result == %{a: %{b: 2}}
     end
 
-    test 'non-map value in right' do
+    test "non-map value in right" do
       result = Utils.deep_merge(%{a: %{b: 1}}, %{a: 2})
       assert result == %{a: 2}
     end
 
-    test 'non-map value in both' do
+    test "non-map value in both" do
       result = Utils.deep_merge(%{a: 1}, %{a: 2})
       assert result == %{a: 2}
     end
   end
+
+  describe "[sub str occurence]" do
+    test "normal occurence case" do
+      assert 2 == Utils.str_occurence("foo bar foobar", "foo")
+      assert 0 == Utils.str_occurence("hello world", "foo")
+    end
+  end
 end