Add default argument to Number#round

spec/std/number_spec.cr

@@ -2,7 +2,7 @@ require "spec"
 
 describe "Number" do
   describe "significant" do
-    it "10 base " do
+    it "10 base" do
       1234.567.significant(1).should eq(1000)
       1234.567.significant(2).should eq(1200)
       1234.567.significant(3).should eq(1230)
@@ -12,13 +12,13 @@ describe "Number" do
       1234.567.significant(7).should eq(1234.567)
     end
 
-    it "2 base " do
+    it "2 base" do
       -1763.116.significant(2, base: 2).should eq(-1536.0)
       753.155.significant(3, base: 2).should eq(768.0)
       15.159.significant(1, base: 2).should eq(16.0)
     end
 
-    it "8 base " do
+    it "8 base" do
       -1763.116.significant(2, base: 8).should eq(-1792.0)
       753.155.significant(3, base: 8).should eq(752.0)
       15.159.significant(1, base: 8).should eq(16.0)
@@ -31,19 +31,25 @@ describe "Number" do
   end
 
   describe "round" do
-    it "10 base " do
+    it "rounds to 0 digits with base 10 from default" do
+      -1763.116.round.should eq(-1763)
+      753.155.round.should eq(753)
+      15.151.round.should eq(15)
+    end
+
+    it "10 base" do
       -1763.116.round(2).should eq(-1763.12)
       753.155.round(2).should eq(753.16)
       15.151.round(2).should eq(15.15)
     end
 
-    it "2 base " do
+    it "2 base" do
       -1763.116.round(2, base: 2).should eq(-1763.0)
       753.155.round(2, base: 2).should eq(753.25)
       15.159.round(2, base: 2).should eq(15.25)
     end
 
-    it "8 base " do
+    it "8 base" do
       -1763.116.round(2, base: 8).should eq(-1763.109375)
       753.155.round(1, base: 8).should eq(753.125)
       15.159.round(0, base: 8).should eq(15.0)

src/number.cr

@@ -209,7 +209,7 @@ struct Number
   # ```
   # -1763.116.round(2) # => -1763.12
   # ```
-  def round(digits, base = 10)
+  def round(digits = 0, base = 10)
     x = self.to_f
     if digits < 0
       y = base ** (-digits)