String.new(capacity:) don't substract termlen

[Bug #20585]

This was changed in 36a06efdd9f0604093dccbaf96d4e2cb17874dc8 because
`String.new(1024)` would end up allocating `1025` bytes, but the problem
with this change is that the caller may be trying to right size a String.

So instead, we should just better document the behavior of `capacity:`.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/-ext-/string/test_capacity.rb b/test/-ext-/string/test_capacity.rb
index 2c6c51fdda..bcca64d85a 100644
--- a/test/-ext-/string/test_capacity.rb
+++ b/test/-ext-/string/test_capacity.rb
@@ -23,7 +23,7 @@ class Test_StringCapacity < Test::Unit::TestCase
   def test_s_new_capacity
     assert_equal("", String.new(capacity: 1000))
     assert_equal(String, String.new(capacity: 1000).class)
-    assert_equal(10_000 - 1, capa(String.new(capacity: 10_000))) # Real capa doesn't account for termlen
+    assert_equal(10_000, capa(String.new(capacity: 10_000)))
 
     assert_equal("", String.new(capacity: -1000))
     assert_equal(capa(String.new(capacity: -10000)), capa(String.new(capacity: -1000)))