feat: ContentType can take an optional default charset (#54)

Signed-off-by: Daniel Azuma <[email protected]>

Author: dazuma

lib/cloud_events/content_type.rb

@@ -21,14 +21,16 @@ class ContentType
     # Parse the given header value.
     #
     # @param string [String] Content-Type header value in RFC 2045 format
+    # @param default_charset [String] Optional. The charset to use if none is
+    #     specified. Defaults to `us-ascii`.
     #
-    def initialize string
+    def initialize string, default_charset: nil
       @string = string
       @media_type = "text"
       @subtype_base = @subtype = "plain"
       @subtype_format = nil
       @params = []
-      @charset = "us-ascii"
+      @charset = default_charset || "us-ascii"
       @error_message = nil
       parse consume_comments string.strip
       @canonical_string = "#{@media_type}/#{@subtype}" +

test/test_content_type.rb

@@ -29,6 +29,18 @@
     assert Ractor.shareable? content_type if defined? Ractor
   end
 
+  it "defaults to us-ascii charset" do
+    content_type = CloudEvents::ContentType.new "application/json"
+    assert_equal "us-ascii", content_type.charset
+    assert Ractor.shareable? content_type if defined? Ractor
+  end
+
+  it "defaults to a given charset" do
+    content_type = CloudEvents::ContentType.new "application/json", default_charset: "utf-8"
+    assert_equal "utf-8", content_type.charset
+    assert Ractor.shareable? content_type if defined? Ractor
+  end
+
   it "recognizes charseet param" do
     content_type = CloudEvents::ContentType.new "application/json; charset=utf-8"
     assert_equal [["charset", "utf-8"]], content_type.params