Add support for parsing command line parameters from other sources than ARGV (#483)

spec/config_spec.cr

@@ -51,7 +51,7 @@ describe "Config" do
         test_option = opt
       end
     end
-    Kemal::CLI.new
+    Kemal::CLI.new ARGV
     test_option.should eq("FOOBAR")
   end
 

src/kemal.cr

@@ -7,25 +7,28 @@ require "./kemal/helpers/*"
 
 module Kemal
   # Overload of `self.run` with the default startup logging.
-  def self.run(port : Int32?)
-    self.run(port) { }
+  def self.run(port : Int32?, args = ARGV)
+    self.run(port, args) { }
   end
 
   # Overload of `self.run` without port.
-  def self.run
-    self.run(nil)
+  def self.run(args = ARGV)
+    self.run(nil, args: args)
   end
 
   # Overload of `self.run` to allow just a block.
-  def self.run(&block)
-    self.run nil, &block
+  def self.run(args = ARGV, &block)
+    self.run(nil, args: args, &block)
   end
 
   # The command to run a `Kemal` application.
   #
   # If *port* is not given Kemal will use `Kemal::Config#port`
-  def self.run(port : Int32? = nil, &block)
-    Kemal::CLI.new
+  #
+  # To use custom command line arguments, set args to nil 
+  #
+  def self.run(port : Int32? = nil, args = ARGV, &block)
+    Kemal::CLI.new args
     config = Kemal.config
     config.setup
     config.port = port if port

src/kemal/cli.cr

@@ -3,18 +3,20 @@ require "option_parser"
 module Kemal
   # Handles all the initialization from the command line.
   class CLI
-    def initialize
+    def initialize(args)
       @ssl_enabled = false
       @key_file = ""
       @cert_file = ""
       @config = Kemal.config
       read_env
-      parse
+      if args
+        parse args
+      end
       configure_ssl
     end
 
-    private def parse
-      OptionParser.parse! do |opts|
+    private def parse(args : Array(String))
+      OptionParser.parse args do |opts|
         opts.on("-b HOST", "--bind HOST", "Host to bind (defaults to 0.0.0.0)") do |host_binding|
           @config.host_binding = host_binding
         end