add test cases for floor, inifinite?, truncate, ceil, and round

test/t/float.rb

@@ -65,7 +65,11 @@ assert('Float#==', '15.2.9.3.7') do
 end
 
 assert('Float#ceil', '15.2.9.3.8') do
-  3.123456789.ceil == 4
+  a = 3.123456789.ceil
+  b = 3.0.ceil
+  c = -3.123456789.ceil
+  d = -3.0.ceil
+  a == 4 and b == 3 and c == -3 and d == -3
 end
 
 assert('Float#finite?', '15.2.9.3.9') do
@@ -74,20 +78,34 @@ assert('Float#finite?', '15.2.9.3.9') do
 end
 
 assert('Float#floor', '15.2.9.3.10') do
-  3.123456789.floor == 3
+  a = 3.123456789.floor
+  b = 3.0.floor
+  c = -3.123456789.floor
+  d = -3.0.floor
+  a == 3 and b == 3 and c == -4 and d == -3
 end
 
 assert('Float#infinite?', '15.2.9.3.11') do
-  not 3.123456789.infinite? and
-    (1.0 / 0.0).infinite?
+  a = 3.123456789.infinite?
+  b = (1.0 / 0.0).infinite?
+  c = (-1.0 / 0.0).infinite?
+
+  a == nil and b == 1 and c == -1
 end
 
 assert('Float#round', '15.2.9.3.12') do
   a = 3.123456789.round
   b = 3.5.round
   c = 3.499999999.round
+  d = (-3.123456789).round
+  e = (-3.5).round
+  f = 12345.67.round(-1)
+  g = 3.123456789.round(0)
+  h = 3.123456789.round(1)
+  i = 3.123456789.round(4)
 
-  a == 3 and b == 4 and c == 3
+  a == 3 and b == 4 and c == 3 and d == -3 and e == -4 and
+    f == 12350 and g == 3 and h == 3.1 and i == 3.1235
 end
 
 assert('Float#to_f', '15.2.9.3.13') do
@@ -101,5 +119,5 @@ assert('Float#to_i', '15.2.9.3.14') do
 end
 
 assert('Float#truncate', '15.2.9.3.15') do
-  3.123456789.truncate == 3
+  3.123456789.truncate == 3 and -3.1.truncate == -3
 end