fix to_param to maximize content

The documentation states that parameter values longer than 20 characters
will be truncated by words, but the example shows that a parameter based
on "David Heinemeier Hansson" (with id: 125) becomes "125-david" when
"David Heinemeier".length == 16 so why so short?

The answer lies in the use of the #truncate option omission: nil which
seems to have been intended to mean "nothing", but which actually causes
the default string "..." to be used. This causes #truncate to cleave
words until the "..." can be added and still remain within the requested
size of 20 characters.

The better option is omission: '' (which is probably what was originally
intended).

Furthermore, since the use of #parameterize will remove non-alphanumeric
characters, we can maximize the useful content of the output by calling
parameterize first and then giving truncate a separator: /-/ rather than
a space.

1 files changed, 28 insertions, 2 deletions

diff --git a/activerecord/test/cases/integration_test.rb b/activerecord/test/cases/integration_test.rb
index 08a186ae07..97a0cdb5db 100644
--- a/activerecord/test/cases/integration_test.rb
+++ b/activerecord/test/cases/integration_test.rb
@@ -29,10 +29,30 @@ class IntegrationTest < ActiveRecord::TestCase
     assert_equal '4-flamboyant-software', firm.to_param
   end
 
+  def test_to_param_class_method_truncates_words_properly
+    firm = Firm.find(4)
+    firm.name << ', Inc.'
+    assert_equal '4-flamboyant-software', firm.to_param
+  end
+
+  def test_to_param_class_method_truncates_after_parameterize
+    firm = Firm.find(4)
+    firm.name = "Huey, Dewey, & Louie LLC"
+    #               123456789T123456789v
+    assert_equal '4-huey-dewey-louie-llc', firm.to_param
+  end
+
+  def test_to_param_class_method_truncates_after_parameterize_with_hyphens
+    firm = Firm.find(4)
+    firm.name = "Door-to-Door Wash-n-Fold Service"
+    #               123456789T123456789v
+    assert_equal '4-door-to-door-wash-n', firm.to_param
+  end
+
   def test_to_param_class_method_truncates
     firm = Firm.find(4)
     firm.name = 'a ' * 100
-    assert_equal '4-a-a-a-a-a-a-a-a-a', firm.to_param
+    assert_equal '4-a-a-a-a-a-a-a-a-a-a', firm.to_param
   end
 
   def test_to_param_class_method_truncates_edge_case
@@ -41,10 +61,16 @@ class IntegrationTest < ActiveRecord::TestCase
     assert_equal '4-david', firm.to_param
   end
 
+  def test_to_param_class_method_truncates_case_shown_in_doc
+    firm = Firm.find(4)
+    firm.name = 'David Heinemeier Hansson'
+    assert_equal '4-david-heinemeier', firm.to_param
+  end
+
   def test_to_param_class_method_squishes
     firm = Firm.find(4)
     firm.name = "ab \n" * 100
-    assert_equal '4-ab-ab-ab-ab-ab-ab', firm.to_param
+    assert_equal '4-ab-ab-ab-ab-ab-ab-ab', firm.to_param
   end
 
   def test_to_param_class_method_multibyte_character