mruby-compar-ext (clamp): found a bug by newly added test

Translate CRuby's logic (in C) to Ruby.

mrbgems/mruby-compar-ext/mrblib/compar.rb

@@ -41,52 +41,35 @@ module Comparable
   #     100.clamp(0...100)       # ArgumentError
   #
   def clamp(min, max=nil)
+
     if max.nil?
       if min.kind_of?(Range)
         max = min.end
-        if max.nil?
-          max = self
-        elsif min.exclude_end?
+        if !max.nil? && min.exclude_end?
           raise ArgumentError, "cannot clamp with an exclusive range"
         end
         min = min.begin
-        if min.nil?
-          min = self
-        end
-      elsif min.nil? or min < self
-        return self
-      else
-        return min
       end
     end
-    if min.nil?
-      if self < max
-        return self
-      else
-        return max
+
+    if !min.nil? && !max.nil?
+      cmp = min <=> max
+      if cmp.nil?
+        raise ArgumentError, "comparison of #{min.class} with #{max.class} failed"
+      elsif cmp > 0
+        raise ArgumentError, "min argument must be smaller than max argument"
       end
     end
-    c = min <=> max
-    if c.nil?
-      raise ArgumentError, "comparison of #{min.class} with #{max.class} failed"
-    elsif c > 0
-      raise ArgumentError, "min argument must be smaller than max argument"
+
+    unless min.nil?
+      cmp = self <=> min
+      return self if cmp == 0
+      return min if cmp < 0
     end
-    c = self <=> min
-    if c.nil?
-      raise ArgumentError, "comparison of #{self.class} with #{min.class} failed"
-    elsif c == 0
-      return self
-    elsif c < 0
-      return min
-    end
-    c = self <=> max
-    if c.nil?
-      raise ArgumentError, "comparison of #{self.class} with #{max.class} failed"
-    elsif c > 0
-      return max
-    else
-      return self
+    unless max.nil?
+      cmp = self <=> max
+      return max if cmp > 0
     end
+    return self
   end
 end