Add quote_boundary opt to content_type/3

lib/multipart.ex

@@ -70,9 +70,17 @@ defmodule Multipart do
       iex> Multipart.content_type(multipart, "multipart/mixed")
       "multipart/mixed; boundary=\\"==abc123==\\""
   """
-  @spec content_type(Multipart.t(), String.t()) :: String.t()
-  def content_type(%__MODULE__{boundary: boundary}, mime_type) do
-    [mime_type, "boundary=\"#{boundary}\""]
+  @spec content_type(Multipart.t(), String.t(), Keyword.t()) :: String.t()
+  def content_type(%__MODULE__{boundary: boundary}, mime_type, opts \\ []) do
+    quote_boundary = opts |> Keyword.get(:quote_boundary, true)
+
+    boundary =
+      case quote_boundary do
+        true -> "\"#{boundary}\""
+        false -> boundary
+      end
+
+    [mime_type, "boundary=#{boundary}"]
     |> Enum.join("; ")
   end
 

test/multipart_test.exs

@@ -124,6 +124,20 @@ defmodule MultipartTest do
     assert output == expected_output
   end
 
+  describe "content_type/3" do
+    test "returns Content-Type header with quoted boundary by default" do
+      multipart = Multipart.new("myboundary")
+      content_type = Multipart.content_type(multipart, "multipart/form-data")
+      assert content_type == "multipart/form-data; boundary=\"myboundary\""
+    end
+
+    test "returns Content-Type header with unquoted boundary when specified" do
+      multipart = Multipart.new("myboundary")
+      content_type = Multipart.content_type(multipart, "multipart/form-data", quote_boundary: false)
+      assert content_type == "multipart/form-data; boundary=myboundary"
+    end
+  end
+
   defp file_path(path) do
     Path.join(__DIR__, path)
   end