diff --git a/test/ruby/test_sprintf_comb.rb b/test/ruby/test_sprintf_comb.rb
index 261732bcbc..20852f9f2f 100644
--- a/test/ruby/test_sprintf_comb.rb
+++ b/test/ruby/test_sprintf_comb.rb
@@ -107,7 +107,9 @@ class TestSprintfComb < Test::Unit::TestCase
   ]
   VS.reverse!
 
-  def combination(*args, &b)
+  FLAGS = [['', ' '], ['', '#'], ['', '+'], ['', '-'], ['', '0']]
+
+  def self.combination(*args, &b)
     #AllPairs.exhaustive_each(*args, &b)
     AllPairs.each(*args, &b)
   end
@@ -268,17 +270,8 @@ class TestSprintfComb < Test::Unit::TestCase
     str
   end
 
-  def test_format_integer
-    combination(
-        %w[B b d o X x],
-        [nil, 0, 5, 20],
-        ["", ".", ".0", ".8", ".20"],
-        ['', ' '],
-        ['', '#'],
-        ['', '+'],
-        ['', '-'],
-        ['', '0']) {|type, width, precision, sp, hs, pl, mi, zr|
-      format = "%#{sp}#{hs}#{pl}#{mi}#{zr}#{width}#{precision}#{type}"
+  def self.assertions_format_integer(format)
+    proc {
       VS.each {|v|
         r = sprintf format, v
         e = emu_int format, v
@@ -293,6 +286,14 @@ class TestSprintfComb < Test::Unit::TestCase
     }
   end
 
+  combination(%w[B b d o X x],
+              [nil, 0, 5, 20],
+              ["", ".", ".0", ".8", ".20"],
+              *FLAGS) {|type, width, precision, sp, hs, pl, mi, zr|
+    format = "%#{sp}#{hs}#{pl}#{mi}#{zr}#{width}#{precision}#{type}"
+    define_method("test_format_integer(#{format})", assertions_format_integer(format))
+  }
+
   FLOAT_VALUES = [
     -1e100,
     -123456789.0,
@@ -526,17 +527,8 @@ class TestSprintfComb < Test::Unit::TestCase
 
   end
 
-  def test_format_float
-    combination(
-        %w[e E f g G],
-        [nil, 0, 5, 20],
-        ["", ".", ".0", ".8", ".20", ".200"],
-        ['', ' '],
-        ['', '#'],
-        ['', '+'],
-        ['', '-'],
-        ['', '0']) {|type, width, precision, sp, hs, pl, mi, zr|
-      format = "%#{sp}#{hs}#{pl}#{mi}#{zr}#{width}#{precision}#{type}"
+  def self.assertions_format_float(format)
+    proc {
       FLOAT_VALUES.each {|v|
         r = sprintf format, v
         e = emu_float format, v
@@ -550,4 +542,12 @@ class TestSprintfComb < Test::Unit::TestCase
       }
     }
   end
+
+  combination(%w[e E f g G],
+              [nil, 0, 5, 20],
+              ["", ".", ".0", ".8", ".20", ".200"],
+              *FLAGS) {|type, width, precision, sp, hs, pl, mi, zr|
+    format = "%#{sp}#{hs}#{pl}#{mi}#{zr}#{width}#{precision}#{type}"
+    define_method("test_format_float(#{format})", assertions_format_float(format))
+  }
 end