Warning message is printed when an unsupported version of a http libr…

…ary is loaded.

lib/webmock.rb

@@ -6,23 +6,14 @@
 require 'webmock/deprecation'
 require 'webmock/version'
 
-require 'webmock/http_lib_adapters/http_lib_adapter_registry'
-require 'webmock/http_lib_adapters/http_lib_adapter'
-require 'webmock/http_lib_adapters/net_http'
-require 'webmock/http_lib_adapters/httpclient_adapter'
-require 'webmock/http_lib_adapters/patron_adapter'
-require 'webmock/http_lib_adapters/curb_adapter'
-require 'webmock/http_lib_adapters/em_http_request_adapter'
-require 'webmock/http_lib_adapters/typhoeus_hydra_adapter'
-require 'webmock/http_lib_adapters/excon_adapter'
-
 require 'webmock/errors'
 
 require 'webmock/util/uri'
 require 'webmock/util/headers'
 require 'webmock/util/hash_counter'
 require 'webmock/util/hash_keys_stringifier'
 require 'webmock/util/json'
+require 'webmock/util/version_checker'
 
 require 'webmock/matchers/hash_including_matcher'
 
@@ -42,4 +33,17 @@
 require 'webmock/request_registry'
 require 'webmock/stub_registry'
 require 'webmock/api'
+
+require 'webmock/http_lib_adapters/http_lib_adapter_registry'
+require 'webmock/http_lib_adapters/http_lib_adapter'
+require 'webmock/http_lib_adapters/net_http'
+require 'webmock/http_lib_adapters/httpclient_adapter'
+require 'webmock/http_lib_adapters/patron_adapter'
+require 'webmock/http_lib_adapters/curb_adapter'
+require 'webmock/http_lib_adapters/em_http_request_adapter'
+require 'webmock/http_lib_adapters/typhoeus_hydra_adapter'
+require 'webmock/http_lib_adapters/excon_adapter'
+
 require 'webmock/webmock'
+
+

lib/webmock/http_lib_adapters/curb_adapter.rb

@@ -5,6 +5,8 @@
 end
 
 if defined?(Curl)
+  WebMock::VersionChecker.new('Curb', Gem.loaded_specs['curb'].version.to_s, '0.7.16').check_version!
+
   module WebMock
     module HttpLibAdapters
       class CurbAdapter < HttpLibAdapter

lib/webmock/http_lib_adapters/excon_adapter.rb

@@ -5,6 +5,7 @@
 end
 
 if defined?(Excon)
+  WebMock::VersionChecker.new('Excon', Excon::VERSION, '0.9.6').check_version!
 
   module WebMock
     module HttpLibAdapters

lib/webmock/http_lib_adapters/typhoeus_hydra_adapter.rb

@@ -5,6 +5,7 @@
 end
 
 if defined?(Typhoeus)
+  WebMock::VersionChecker.new('Typhoeus', Typhoeus::VERSION, '0.3.2').check_version!
 
   module WebMock
     module HttpLibAdapters

lib/webmock/util/version_checker.rb

@@ -0,0 +1,73 @@
+# This code was created based on https://github.com/myronmarston/vcr/blob/master/lib/vcr/util/version_checker.rb
+# Thanks to @myronmarston
+
+module WebMock
+  class VersionChecker
+    def initialize(library_name, library_version, min_patch_level, max_minor_version = nil)
+      @library_name, @library_version = library_name, library_version
+      @min_patch_level, @max_minor_version = min_patch_level, max_minor_version
+
+      @major,     @minor,     @patch     = parse_version(library_version)
+      @min_major, @min_minor, @min_patch = parse_version(min_patch_level)
+      @max_major, @max_minor             = parse_version(max_minor_version) if max_minor_version
+
+      @comparison_result = compare_version
+    end
+
+    def check_version!
+      warn_about_too_low if too_low?
+      warn_about_too_high if too_high?
+    end
+
+  private
+
+    def too_low?
+      @comparison_result == :too_low
+    end
+
+    def too_high?
+      @comparison_result == :too_high
+    end
+
+    def warn_about_too_low
+      warn_in_red "You are using #{@library_name} #{@library_version}. " +
+                  "WebMock supports version #{version_requirement}."
+    end
+
+    def warn_about_too_high
+      warn_in_red "You are using #{@library_name} #{@library_version}. " +
+                  "WebMock is known to work with #{@library_name} #{version_requirement}. " +
+                  "It may not work with this version."
+    end
+
+    def warn_in_red(text)
+      Kernel.warn colorize(text, "\e[31m")
+    end
+
+    def compare_version
+      case
+        when @major < @min_major then :too_low
+        when @max_major && @major > @max_major then :too_high
+        when @major > @min_major then :ok
+        when @minor < @min_minor then :too_low
+        when @max_minor && @minor > @max_minor then :too_high
+        when @minor > @min_minor then :ok
+        when @patch < @min_patch then :too_low
+      end
+    end
+
+    def version_requirement
+      req = ">= #{@min_patch_level}"
+      req += ", < #{@max_major}.#{@max_minor + 1}" if @max_minor
+      req
+    end
+
+    def parse_version(version)
+      version.split('.').map { |v| v.to_i }
+    end
+
+    def colorize(text, color_code)
+      "#{color_code}#{text}\e[0m"
+    end
+  end
+end

spec/unit/util/version_checker_spec.rb

@@ -0,0 +1,59 @@
+require 'spec_helper'
+
+module WebMock
+  describe VersionChecker do
+    it 'prints a warning if the major version is too low' do
+      checker = VersionChecker.new('foo', '0.7.3', '1.0.0', '1.1')
+      Kernel.should_receive(:warn).with("\e[31mYou are using foo 0.7.3. WebMock supports version >= 1.0.0, < 1.2.\e[0m")
+      checker.check_version!
+    end
+
+    it 'prints a warning if the minor version is too low' do
+      checker = VersionChecker.new('foo', '1.0.99', '1.1.3', '1.2')
+      Kernel.should_receive(:warn).with("\e[31mYou are using foo 1.0.99. WebMock supports version >= 1.1.3, < 1.3.\e[0m")
+      checker.check_version!
+    end
+
+    it 'prints a warning if the patch version is too low' do
+      checker = VersionChecker.new('foo', '1.0.8', '1.0.10', '1.2')
+      Kernel.should_receive(:warn).with("\e[31mYou are using foo 1.0.8. WebMock supports version >= 1.0.10, < 1.3.\e[0m")
+      checker.check_version!
+    end
+
+    it 'prints a warning if the patch version is too low and max version is not specified' do
+      checker = VersionChecker.new('foo', '1.0.8', '1.0.10')
+      Kernel.should_receive(:warn).with("\e[31mYou are using foo 1.0.8. WebMock supports version >= 1.0.10.\e[0m")
+      checker.check_version!
+    end
+
+    it 'prints a warning if the major version is too high' do
+      checker = VersionChecker.new('foo', '2.0.0', '1.0.0', '1.1')
+      Kernel.should_receive(:warn).with(/may not work with this version/)
+      checker.check_version!
+    end
+
+    it 'prints a warning if the minor version is too high' do
+      checker = VersionChecker.new('foo', '1.2.0', '1.0.0', '1.1')
+      Kernel.should_receive(:warn).with(/may not work with this version/)
+      checker.check_version!
+    end
+
+    it 'does not raise an error or print a warning when the major version is between the min and max' do
+      checker = VersionChecker.new('foo', '2.0.0', '1.0.0', '3.0')
+      Kernel.should_not_receive(:warn)
+      checker.check_version!
+    end
+
+    it 'does not raise an error or print a warning when the min_patch is 0.6.5, the max_minor is 0.7 and the version is 0.7.3' do
+      checker = VersionChecker.new('foo', '0.7.3', '0.6.5', '0.7')
+      Kernel.should_not_receive(:warn)
+      checker.check_version!
+    end
+
+    it 'does not raise an error or print a warning when the min_patch is 0.6.5, the max_minor is not specified and the version is 0.8.3' do
+      checker = VersionChecker.new('foo', '0.8.3', '0.6.5')
+      Kernel.should_not_receive(:warn)
+      checker.check_version!
+    end
+  end
+end