feat: respond multiple headers with same key

lib/puppeteer/http_request.rb

@@ -217,8 +217,14 @@ def failure
   private def headers_to_array(headers)
     return nil unless headers
 
-    headers.map do |key, value|
-      { name: key, value: value.to_s }
+    headers.flat_map do |key, value|
+      if value.is_a?(Enumerable)
+        value.map do |v|
+          { name: key, value: v.to_s }
+        end
+      else
+        { name: key, value: value.to_s }
+      end
     end
   end
 
@@ -349,7 +355,12 @@ def respond(status: nil, headers: nil, content_type: nil, body: nil, priority: n
 
     mock_response_headers = {}
     headers&.each do |key, value|
-      mock_response_headers[key.downcase] = value
+      mock_response_headers[key.downcase] =
+        if value.is_a?(Enumerable)
+          value.map(&:to_s)
+        else
+          value.to_s
+        end
     end
     if content_type
       mock_response_headers['content-type'] = content_type

spec/integration/request_interception_spec.rb

@@ -36,6 +36,34 @@
 
     page.goto(server_empty_page)
   end
+
+  it 'should allow mocking multiple headers with same key', sinatra: true do
+    page.request_interception = true
+    page.on('request') do |request|
+      request.respond(
+        status: 200,
+        headers: {
+          foo: 'bar',
+          arr: ['1', '2'],
+          'set-cookie': ['first=1', 'second=2'],
+        },
+        body: 'Hello world',
+      )
+    end
+
+    response = page.goto(server_empty_page)
+    cookies = page.cookies
+    first_cookie = cookies.find { |cookie| cookie['name'] == 'first' }
+    second_cookie = cookies.find { |cookie| cookie['name'] == 'second' }
+
+    expect(response.status).to eq(200)
+    expect(response.headers['foo']).to eq('bar')
+    expect(response.headers['arr']).to eq("1\n2")
+    # request.respond() will not trigger Network.responseReceivedExtraInfo
+    # fail to get 'set-cookie' header from response
+    expect(first_cookie['value']).to eq('1')
+    expect(second_cookie['value']).to eq('2')
+  end
 end
 
 # https://github.com/puppeteer/puppeteer/blob/e2e98376b9a3fa9a2501ddc86ff6407f3b59887d/docs/api.md#cooperative-intercept-mode-and-legacy-intercept-mode