1 files changed, 55 insertions, 0 deletions
diff --git a/spec/ruby/core/string/prepend_spec.rb b/spec/ruby/core/string/prepend_spec.rb
new file mode 100644
index 0000000000..5248ea8056
--- /dev/null
+++ b/spec/ruby/core/string/prepend_spec.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: false
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "String#prepend" do
+  it "prepends the given argument to self and returns self" do
+    str = "world"
+    str.prepend("hello ").should equal(str)
+    str.should == "hello world"
+  end
+
+  it "converts the given argument to a String using to_str" do
+    obj = mock("hello")
+    obj.should_receive(:to_str).and_return("hello")
+    a = " world!".prepend(obj)
+    a.should == "hello world!"
+  end
+
+  it "raises a TypeError if the given argument can't be converted to a String" do
+    -> { "hello ".prepend [] }.should raise_error(TypeError)
+    -> { 'hello '.prepend mock('x') }.should raise_error(TypeError)
+  end
+
+  it "raises a FrozenError when self is frozen" do
+    a = "hello"
+    a.freeze
+
+    -> { a.prepend "" }.should raise_error(FrozenError)
+    -> { a.prepend "test" }.should raise_error(FrozenError)
+  end
+
+  it "works when given a subclass instance" do
+    a = " world"
+    a.prepend StringSpecs::MyString.new("hello")
+    a.should == "hello world"
+  end
+
+  it "takes multiple arguments" do
+    str = " world"
+    str.prepend "he", "", "llo"
+    str.should == "hello world"
+  end
+
+  it "prepends the initial value when given arguments contain 2 self" do
+    str = "hello"
+    str.prepend str, str
+    str.should == "hellohellohello"
+  end
+
+  it "returns self when given no arguments" do
+    str = "hello"
+    str.prepend.should equal(str)
+    str.should == "hello"
+  end
+end