Replace “can not” with “cannot”.

activemodel/test/cases/attribute_test.rb

@@ -204,7 +204,7 @@ module ActiveModel
       assert_not_predicate unchanged, :changed?
     end
 
-    test "an attribute can not be mutated if it has not been read,
+    test "an attribute cannot be mutated if it has not been read,
       and skips expensive calculations" do
       type_which_raises_from_all_methods = Object.new
       attribute = Attribute.from_database(:foo, "bar", type_which_raises_from_all_methods)

activerecord/lib/active_record/errors.rb

@@ -68,7 +68,7 @@ module ActiveRecord
 
   # Raised by {ActiveRecord::Base#save!}[rdoc-ref:Persistence#save!] and
   # {ActiveRecord::Base.create!}[rdoc-ref:Persistence::ClassMethods#create!]
-  # methods when a record is invalid and can not be saved.
+  # methods when a record is invalid and cannot be saved.
   class RecordNotSaved < ActiveRecordError
     attr_reader :record
 

activerecord/lib/active_record/relation/finder_methods.rb

@@ -7,7 +7,7 @@ module ActiveRecord
     ONE_AS_ONE = "1 AS one"
 
     # Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]).
-    # If one or more records can not be found for the requested ids, then ActiveRecord::RecordNotFound will be raised.
+    # If one or more records cannot be found for the requested ids, then ActiveRecord::RecordNotFound will be raised.
     # If the primary key is an integer, find by id coerces its arguments by using +to_i+.
     #
     #   Person.find(1)          # returns the object for ID = 1

activerecord/lib/active_record/relation/query_methods.rb

@@ -1117,7 +1117,7 @@ module ActiveRecord
             o.reverse
           when String
             if does_not_support_reverse?(o)
-              raise IrreversibleOrderError, "Order #{o.inspect} can not be reversed automatically"
+              raise IrreversibleOrderError, "Order #{o.inspect} cannot be reversed automatically"
             end
             o.split(",").map! do |s|
               s.strip!

activerecord/lib/active_record/validations/uniqueness.rb

@@ -25,7 +25,7 @@ module ActiveRecord
           if finder_class.primary_key
             relation = relation.where.not(finder_class.primary_key => record.id_in_database)
           else
-            raise UnknownPrimaryKey.new(finder_class, "Can not validate uniqueness for persisted record without primary key.")
+            raise UnknownPrimaryKey.new(finder_class, "Cannot validate uniqueness for persisted record without primary key.")
           end
         end
         relation = scope_relation(record, relation)

activerecord/test/cases/validations/uniqueness_validation_test.rb

@@ -555,7 +555,7 @@ class UniquenessValidationTest < ActiveRecord::TestCase
       abc.save!
     end
     assert_match(/\AUnknown primary key for table dashboards in model/, e.message)
-    assert_match(/Can not validate uniqueness for persisted record without primary key.\z/, e.message)
+    assert_match(/Cannot validate uniqueness for persisted record without primary key.\z/, e.message)
   end
 
   def test_validate_uniqueness_ignores_itself_when_primary_key_changed

guides/source/active_record_migrations.md

@@ -484,7 +484,7 @@ add_foreign_key :articles, :authors
 
 This adds a new foreign key to the `author_id` column of the `articles`
 table. The key references the `id` column of the `authors` table. If the
-column names can not be derived from the table names, you can use the
+column names cannot be derived from the table names, you can use the
 `:column` and `:primary_key` options.
 
 Rails will generate a name for every foreign key starting with