diff --git a/core/random/alphanumeric_spec.rb b/core/random/alphanumeric_spec.rb
new file mode 100644
index 0000000000..e57b8de7a4
--- /dev/null
+++ b/core/random/alphanumeric_spec.rb
@@ -0,0 +1,6 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/random/formatter/alphanumeric'
+
+describe "Random#alphanumeric" do
+  it_behaves_like :random_alphanumeric, :alphanumeric, Random
+end
diff --git a/library/securerandom/alphanumeric_spec.rb b/library/securerandom/alphanumeric_spec.rb
new file mode 100644
index 0000000000..ecfac8ea5a
--- /dev/null
+++ b/library/securerandom/alphanumeric_spec.rb
@@ -0,0 +1,8 @@
+require_relative '../../spec_helper'
+require_relative '../../shared/random/formatter/alphanumeric'
+
+require 'securerandom'
+
+describe "SecureRandom#alphanumeric" do
+  it_behaves_like :random_alphanumeric, :alphanumeric, SecureRandom
+end
diff --git a/shared/random/formatter/alphanumeric.rb b/shared/random/formatter/alphanumeric.rb
new file mode 100644
index 0000000000..6d5843ae1f
--- /dev/null
+++ b/shared/random/formatter/alphanumeric.rb
@@ -0,0 +1,50 @@
+require_relative '../../../spec_helper'
+
+describe :random_alphanumeric, shared: true do
+  ruby_version_is "3.1" do
+    require 'random/formatter'
+
+    it "generates a random alphanumeric string" do
+      @object.send(@method).should =~ /\A[A-Za-z0-9]+\z/
+    end
+
+    it "has a default size of 16 characters" do
+      @object.send(@method).size.should == 16
+    end
+
+    it "accepts a 'size' argument" do
+      @object.send(@method, 10).size.should == 10
+    end
+
+    it "uses the default size if 'nil' is given as size argument" do
+      @object.send(@method, nil).size.should == 16
+    end
+
+    it "raises an ArgumentError if the size is not numeric" do
+      -> {
+        @object.send(@method, "10")
+      }.should raise_error(ArgumentError)
+    end
+
+    it "does not coerce the size argument with #to_int" do
+      size = mock("size")
+      size.should_not_receive(:to_int)
+      -> {
+        @object.send(@method, size)
+      }.should raise_error(ArgumentError)
+    end
+
+    ruby_version_is "3.3" do
+      it "accepts a 'chars' argument with the output alphabet" do
+        @object.send(@method, chars: ['a', 'b']).should =~ /\A[ab]+\z/
+      end
+
+      it "converts the elements of chars using #to_s" do
+        to_s = mock("to_s")
+        to_s.should_receive(:to_s).and_return("[mock to_s]")
+        # Using 1 value in chars results in an infinite loop
+        @object.send(@method, 1, chars: [to_s, to_s]).should == "[mock to_s]"
+      end
+    end
+  end
+end