1 files changed, 45 insertions, 0 deletions
diff --git a/spec/ruby/core/string/start_with_spec.rb b/spec/ruby/core/string/start_with_spec.rb
new file mode 100644
index 0000000000..b85081037d
--- /dev/null
+++ b/spec/ruby/core/string/start_with_spec.rb
@@ -0,0 +1,45 @@
+# -*- encoding: utf-8 -*-
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes.rb', __FILE__)
+
+describe "String#start_with?" do
+  it "returns true only if beginning match" do
+    s = "hello"
+    s.start_with?('h').should be_true
+    s.start_with?('hel').should be_true
+    s.start_with?('el').should be_false
+  end
+
+  it "returns true only if any beginning match" do
+    "hello".start_with?('x', 'y', 'he', 'z').should be_true
+  end
+
+  it "returns true if the search string is empty" do
+    "hello".start_with?("").should be_true
+    "".start_with?("").should be_true
+  end
+
+  it "converts its argument using :to_str" do
+    s = "hello"
+    find = mock('h')
+    find.should_receive(:to_str).and_return("h")
+    s.start_with?(find).should be_true
+  end
+
+  it "ignores arguments not convertible to string" do
+    "hello".start_with?().should be_false
+    lambda { "hello".start_with?(1) }.should  raise_error(TypeError)
+    lambda { "hello".start_with?(["h"]) }.should  raise_error(TypeError)
+    lambda { "hello".start_with?(1, nil, "h").should }.should raise_error(TypeError)
+  end
+
+  it "uses only the needed arguments" do
+    find = mock('h')
+    find.should_not_receive(:to_str)
+    "hello".start_with?("h",find).should be_true
+  end
+
+  it "works for multibyte strings" do
+    "céréale".start_with?("cér").should be_true
+  end
+end