Auto-generate stable fixture UUIDs on PostgreSQL.

Fixes: #11524

1 files changed, 47 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/core_ext/securerandom.rb b/activesupport/lib/active_support/core_ext/securerandom.rb
new file mode 100644
index 0000000000..fec8f7c0ec
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/securerandom.rb
@@ -0,0 +1,47 @@
+module SecureRandom
+  UUID_DNS_NAMESPACE  = "k\xA7\xB8\x10\x9D\xAD\x11\xD1\x80\xB4\x00\xC0O\xD40\xC8" #:nodoc:
+  UUID_URL_NAMESPACE  = "k\xA7\xB8\x11\x9D\xAD\x11\xD1\x80\xB4\x00\xC0O\xD40\xC8" #:nodoc:
+  UUID_OID_NAMESPACE  = "k\xA7\xB8\x12\x9D\xAD\x11\xD1\x80\xB4\x00\xC0O\xD40\xC8" #:nodoc:
+  UUID_X500_NAMESPACE = "k\xA7\xB8\x14\x9D\xAD\x11\xD1\x80\xB4\x00\xC0O\xD40\xC8" #:nodoc:
+  
+  # Generates a v5 non-random UUID (Universally Unique IDentifier).
+  #
+  # Using Digest::MD5 generates version 3 UUIDs; Digest::SHA1 generates version 5 UUIDs.
+  # ::uuid_from_hash always generates the same UUID for a given name and namespace combination.
+  #
+  # See RFC 4122 for details of UUID at: http://www.ietf.org/rfc/rfc4122.txt
+  def self.uuid_from_hash(hash_class, uuid_namespace, name)
+    if hash_class == Digest::MD5
+      version = 3
+    elsif hash_class == Digest::SHA1
+      version = 5
+    else
+      raise ArgumentError, "Expected Digest::SHA1 or Digest::MD5, got #{hash_class.name}."
+    end
+
+    hash = hash_class.new
+    hash.update(uuid_namespace)
+    hash.update(name)
+
+    ary = hash.digest.unpack('NnnnnN')
+    ary[2] = (ary[2] & 0x0FFF) | (version << 12)
+    ary[3] = (ary[3] & 0x3FFF) | 0x8000
+
+    "%08x-%04x-%04x-%04x-%04x%08x" % ary
+  end
+
+  # Convenience method for ::uuid_from_hash using Digest::MD5.
+  def self.uuid_v3(uuid_namespace, name)
+    self.uuid_from_hash(Digest::MD5, uuid_namespace, name)
+  end
+
+  # Convenience method for ::uuid_from_hash using Digest::SHA1.
+  def self.uuid_v5(uuid_namespace, name)
+    self.uuid_from_hash(Digest::SHA1, uuid_namespace, name)
+  end
+
+  class << self
+    # Alias for ::uuid.
+    alias_method :uuid_v4, :uuid
+  end
+end