Handle bad constant names in Slop.option_defined?

Closes #198

2 files changed, 21 insertions, 0 deletions

diff --git a/lib/slop.rb b/lib/slop.rb
index 9526097..45edb7f 100644
--- a/lib/slop.rb
+++ b/lib/slop.rb
@@ -31,6 +31,10 @@ module Slop
   # Returns true if an option is defined.
   def self.option_defined?(name)
     const_defined?(string_to_option(name.to_s))
+  rescue NameError
+    # If a NameError is raised, it wasn't a valid constant name,
+    # and thus couldn't have been defined.
+    false
   end
 
   # Example:
diff --git a/test/slop_test.rb b/test/slop_test.rb
new file mode 100644
index 0000000..f6fb408
--- /dev/null
+++ b/test/slop_test.rb
@@ -0,0 +1,17 @@
+require "test_helper"
+
+describe Slop do
+  describe ".option_defined?" do
+    it "handles bad constant names" do
+      assert_equal false, Slop.option_defined?("Foo?Bar")
+    end
+
+    it "returns false if the option is not defined" do
+      assert_equal false, Slop.option_defined?("Foo")
+    end
+
+    it "returns true if the option is defined" do
+      assert_equal true, Slop.option_defined?("String")
+    end
+  end
+end