Add File.atomic_write to prevent users from seeing half written files. Useful for situations like Page Caching and the like. [Koz]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@6262 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 29 insertions, 0 deletions

diff --git a/activesupport/test/core_ext/file_test.rb b/activesupport/test/core_ext/file_test.rb
new file mode 100644
index 0000000000..a7a8324125
--- /dev/null
+++ b/activesupport/test/core_ext/file_test.rb
@@ -0,0 +1,29 @@
+require File.dirname(__FILE__) + '/../abstract_unit'
+
+class AtomicWriteTest < Test::Unit::TestCase
+  
+  def test_atomic_write_without_errors
+    contents  = "Atomic Text"
+    File.atomic_write(file_name) do |file|
+      file.write(contents)
+      assert !File.exists?(file_name)
+    end
+    assert File.exists?(file_name)
+    assert_equal contents, File.read(file_name)
+  ensure
+    File.unlink(file_name)
+  end
+  
+  def test_atomic_write_doesnt_write_when_block_raises
+    File.atomic_write(file_name) do |file|
+      file.write("testing")
+      raise "something bad"
+    end
+  rescue
+    assert !File.exists?(file_name)
+  end
+  
+  def file_name
+    "atomic.file"
+  end
+end