assert and deny methods that do a few things

Author: sconover

LICENSE

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+Copyright (c) 2010 Steve Conover
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README

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+Wrong provides an assert method that takes a block, and interrogates the block to create rich assertion failure messages.
+
+It's an offshoot of predicated.
+http://github.com/sconover/predicated
+
+Inspired by assert { 2.0 }
+http://assert2.rubyforge.org/
+
+Tracker project:
+http://www.pivotaltracker.com/projects/95014
+
+“I think it's wrong that only one company makes the game Monopoly.” -Steven Wright

lib/wrong.rb

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+$LOAD_PATH.unshift(File.dirname(__FILE__))
+
+require "wrong/assert"

lib/wrong/assert.rb

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+require "predicated/predicate"
+require "predicated/from/callable_object"
+require "predicated/to/sentence"
+
+module Wrong
+  module Assert
+    def assert(&block)
+      raise FailureMessageForBlock.new(block).failure_str unless block.call
+    end
+
+    def deny(&block)
+      raise FailureMessageForBlock.new(block).reverse_failure_str if block.call
+    end
+    
+    class FailureMessageForBlock
+      include Predicated
+      
+      def initialize(block)
+        @block = block
+      end
+
+      def failure_str
+        Predicate.from_callable_object(@block).to_negative_sentence
+      end
+
+      def reverse_failure_str
+        Predicate.from_callable_object(@block).to_sentence
+      end
+    end
+  end
+end

test/basic_assert_test.rb

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+require "test/test_helper"
+
+require "wrong/assert"
+
+apropos "basic assert features" do
+  
+  before do
+    @m = Module.new do
+      extend Wrong::Assert
+    end
+  end
+  
+  apropos "pass/fail basics" do
+    test "passes when the result is true.  deny does the reverse" do
+      @m.assert{true}
+      @m.assert{1==1}
+
+      @m.deny{false}
+      @m.deny{1==2}
+    end
+  
+    test "fails when result is false.  deny does the reverse" do
+      assert_raises(RuntimeError) { @m.assert{false} }
+      assert_raises(RuntimeError) { @m.assert{1==2} }
+      
+      assert_raises(RuntimeError) { @m.deny{true} }
+      assert_raises(RuntimeError) { @m.deny{1==1} }
+    end
+  
+    class MyError < StandardError; end
+  
+    test "both deny and assert fail when an error is thrown.  bubbles up the error." do
+      assert_raises(MyError) { @m.assert{ raise MyError.new } }
+      assert_raises(MyError) { @m.deny{ raise MyError.new } }
+    end
+  end
+  
+end

test/failures_test.rb

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+require "test/test_helper"
+
+require "wrong/assert"
+
+apropos "failures" do
+  
+  before do
+    @m = Module.new do
+      extend Wrong::Assert
+    end
+  end
+  
+  def get_error
+    error = nil
+    begin
+      yield
+    rescue Exception => e
+      error = e
+    end
+    e
+  end
+  
+  apropos "simple" do
+    test "raw boolean failure" do
+      assert_match "false", get_error{@m.assert{false}}.message
+      assert_match "true", get_error{@m.deny{true}}.message
+    end
+  
+    test "equality failure" do
+      assert_match "1 is not equal to 2", get_error{@m.assert{1==2}}.message
+      assert_match "1 is equal to 1", get_error{@m.deny{1==1}}.message
+    end
+  
+    test "failure of basic operations" do
+      assert_match "1 is not greater than 2", get_error{@m.assert{1>2}}.message
+      assert_match "2 is not less than 1", get_error{@m.assert{2<1}}.message
+      assert_match "1 is not greater than or equal to 2", get_error{@m.assert{1>=2}}.message
+      assert_match "2 is not less than or equal to 1", get_error{@m.assert{2<=1}}.message
+
+      assert_match "2 is greater than 1", get_error{@m.deny{2>1}}.message
+      assert_match "1 is less than 2", get_error{@m.deny{1<2}}.message
+      assert_match "2 is greater than or equal to 1", get_error{@m.deny{2>=1}}.message
+      assert_match "1 is less than or equal to 2", get_error{@m.deny{1<=2}}.message
+    end
+    
+    class Color
+      attr_reader :name
+      def initialize(name)
+        @name = name
+      end
+    
+      def ==(other)
+        other.is_a?(Color) && @name == other.name
+      end
+      
+      def inspect
+        "Color:#{@name}"
+      end
+    end
+    
+    test "object failure" do
+      assert_match "'Color:red' is not equal to 2", get_error{@m.assert{Color.new("red")==2}}.message
+    end
+    
+    test %{multiline assert block shouldn't look any different 
+           than when there everything is on one line} do
+      assert_match("1 is not equal to 2", get_error{@m.assert{
+        1==
+        2
+      }}.message)
+    end
+
+  end
+  
+  apropos "accessing and printing values set outside of the assert" do
+    test "use a value in the assert defined outside of it" do
+      a = 1
+      assert_match "1 is not equal to 2", get_error{@m.assert{a==2}}.message
+      assert_match "1 is equal to 1", get_error{@m.deny{a==1}}.message
+    end
+  end
+  
+  apropos "the assert block has many statements" do
+    test "only pay attention to the final statement" do
+      assert_match("1 is not equal to 2", get_error{@m.assert{
+        a = "aaa"
+        b = 1 + 2
+        c = ["foo", "bar"].length / 3
+        if a=="aaa"
+          b = 4
+        end; 1==2
+      }}.message)
+    end
+  end
+end

test/suite.rb

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+#simple way to make sure requires are isolated
+result = Dir["test/**/*_test.rb"].collect{|test_file| system("ruby #{test_file}") }.uniq == [true]
+puts "suite " + (result ? "passed" : "FAILED")
+exit(result ? 0 : 1)

test/test_helper.rb

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+dir = File.dirname(__FILE__)
+$LOAD_PATH.unshift "#{dir}/../lib"
+$LOAD_PATH.unshift "../predicated/lib"
+require "rubygems"
+require "minitest/spec"
+require "minitest/unit"
+require "pp"
+
+class MiniTest::Unit::TestCase
+  
+end
+
+module Kernel
+  alias_method :apropos, :describe
+  
+  def xapropos(str)
+    puts "x'd out 'apropos \"#{str}\"'"
+  end
+end
+
+class MiniTest::Spec
+  include MiniTest::Assertions
+  
+  class << self
+    alias_method :test, :it
+    
+    def xtest(str)
+      puts "x'd out 'test \"#{str}\"'"
+    end
+
+  end
+end
+
+MiniTest::Unit.autorun