Change the spell checker algorithm

Before: [:read, :rand, ...]
                ^�(J~~~~�(B only select this

After:  [:read, :rand, ...]
         ^�(J~~~~~~~~~~~�(B select :rand and also take elements before :rand

closes #60

lib/did_you_mean/spell_checkable.rb

@@ -16,11 +16,13 @@ def corrections
 
         # Correct mistypes
         threshold   = (input.length * 0.25).ceil
-        corrections = seed.select {|c| Levenshtein.distance(normalize(c), input) <= threshold }
+        has_mistype = seed.rindex {|c| Levenshtein.distance(normalize(c), input) <= threshold }
 
-        # Correct misspells
-        if corrections.empty?
-          corrections = seed.select do |candidate|
+        corrections = if has_mistype
+          seed.take(has_mistype + 1)
+        else
+          # Correct misspells
+          seed.select do |candidate|
             candidate = normalize(candidate)
             length    = input.length < candidate.length ? input.length : candidate.length
 

test/spell_checker_test.rb

@@ -21,6 +21,7 @@ def test_spell_checker_corrects_mistypes
 
     assert_spell %w(gsub! gsub),     input: 'gsuv!', dictionary: %w(sub gsub gsub!)
     assert_spell %w(sub! sub gsub!), input: 'ssub!', dictionary: %w(sub sub! gsub gsub!)
+    assert_spell %i(read rand),      input: 'raed',  dictionary: File.methods + File.private_methods
 
     group_methods = %w(groups group_url groups_url group_path)
     assert_spell 'groups', input: 'group',  dictionary: group_methods