Add more check_headers to HTTP::Server::Response (#11253)

spec/std/http/server/response_spec.cr

@@ -151,12 +151,27 @@ describe HTTP::Server::Response do
     io.to_s.should eq("HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\nContent-Length: 5\r\n\r\nHello")
   end
 
+  it "sets content type after headers sent" do
+    io = IO::Memory.new
+    response = Response.new(io)
+    response.print("Hello")
+    response.flush
+    expect_raises(IO::Error, "Headers already sent") do
+      response.content_type = "text/plain"
+    end
+  end
+
   it "sets status code" do
     io = IO::Memory.new
     response = Response.new(io)
     return_value = response.status_code = 201
     return_value.should eq 201
     response.status.should eq HTTP::Status::CREATED
+    response.print("Hello")
+    response.flush
+    expect_raises(IO::Error, "Headers already sent") do
+      response.status_code = 201
+    end
   end
 
   it "retrieves status code" do
@@ -175,6 +190,19 @@ describe HTTP::Server::Response do
     io.to_s.should eq("HTTP/1.0 404 Not Found\r\nContent-Length: 0\r\n\r\n")
   end
 
+  it "changes status and others after headers sent" do
+    io = IO::Memory.new
+    response = Response.new(io)
+    response.print("Foo")
+    response.flush
+    expect_raises(IO::Error, "Headers already sent") do
+      response.status = :not_found
+    end
+    expect_raises(IO::Error, "Headers already sent") do
+      response.version = "HTTP/1.0"
+    end
+  end
+
   it "flushes" do
     io = IO::Memory.new
     response = Response.new(io)

src/http/server/response.cr

@@ -27,11 +27,19 @@ class HTTP::Server
     property output : IO
 
     # :nodoc:
-    setter version : String
+    def version=(version : String)
+      check_headers
+      @version = version
+    end
 
     # The status code of this response, which must be set before writing the response
     # body. If not set, the default value is 200 (OK).
-    property status : HTTP::Status
+    getter status : HTTP::Status
+
+    def status=(status : HTTP::Status)
+      check_headers
+      @status = status
+    end
 
     # :nodoc:
     property upgrade_handler : (IO ->)?
@@ -60,11 +68,13 @@ class HTTP::Server
 
     # Convenience method to set the `Content-Type` header.
     def content_type=(content_type : String)
+      check_headers
       headers["Content-Type"] = content_type
     end
 
     # Convenience method to set the `Content-Length` header.
     def content_length=(content_length : Int)
+      check_headers
       headers["Content-Length"] = content_length.to_s
     end