Add Time::Span#microseconds, Int#microseconds and Float#microseconds

spec/std/time/span_spec.cr

@@ -100,13 +100,15 @@ describe Time::Span do
     t1.minutes.should eq(3)
     t1.seconds.should eq(4)
     t1.milliseconds.should eq(5)
+    t1.microseconds.should eq(5_000)
     t1.nanoseconds.should eq(5_000_000)
 
     t2.days.should eq(-1)
     t2.hours.should eq(-2)
     t2.minutes.should eq(-3)
     t2.seconds.should eq(-4)
     t2.milliseconds.should eq(-5)
+    t2.microseconds.should eq(-5_000)
     t2.nanoseconds.should eq(-5_000_000)
   end
 
@@ -154,6 +156,8 @@ describe Time::Span do
 
   it "test int extension methods" do
     1_000_000.days.to_s.should eq("1000000.00:00:00")
+    12.microseconds.to_s.should eq("00:00:00.000012000")
+    -12.microseconds.to_s.should eq("-00:00:00.000012000")
   end
 
   it "test float extension methods" do
@@ -166,6 +170,8 @@ describe Time::Span do
     0.5.milliseconds.to_s.should eq("00:00:00.000500000")
     -2.5.milliseconds.to_s.should eq("-00:00:00.002500000")
     2.5.milliseconds.to_s.should eq("00:00:00.002500000")
+    -2.5.microseconds.to_s.should eq("-00:00:00.000002500")
+    2.5.microseconds.to_s.should eq("00:00:00.000002500")
     0.0005.seconds.to_s.should eq("00:00:00.000500000")
 
     1_000_000.5.days.to_s.should eq("1000000.12:00:00")

src/time.cr

@@ -224,6 +224,9 @@ struct Time
   # :nodoc:
   NANOSECONDS_PER_MILLISECOND = 1_000_000_i64
 
+  # :nodoc:
+  NANOSECONDS_PER_MICROSECOND = 1_000_i64
+
   # :nodoc:
   NANOSECONDS_PER_SECOND = 1_000_000_000_i64
 

src/time/span.cr

@@ -182,6 +182,11 @@ struct Time::Span
     nanoseconds / NANOSECONDS_PER_MILLISECOND
   end
 
+  # Returns the number of microseconds of the second (`0..999999`) in this time span.
+  def microseconds : Int32
+    nanoseconds / NANOSECONDS_PER_MICROSECOND
+  end
+
   # Returns the number of nanoseconds of the second (`0..999_999_999`)
   # in this time span.
   def nanoseconds : Int32
@@ -449,6 +454,11 @@ struct Int
     Time::Span.new 0, 0, 0, 0, (self.to_i64 * Time::NANOSECONDS_PER_MILLISECOND)
   end
 
+  # Returns a `Time::Span` of `self` microseconds.
+  def microseconds : Time::Span
+    Time::Span.new 0, 0, 0, 0, (self.to_i64 * Time::NANOSECONDS_PER_MICROSECOND)
+  end
+
   # :nodoc:
   def nanosecond : Time::Span
     nanoseconds
@@ -495,6 +505,11 @@ struct Float
     (self / 1_000).seconds
   end
 
+  # Returns a `Time::Span` of `self` microseconds.
+  def microseconds : Time::Span
+    (self / 1_000_000).seconds
+  end
+
   # Returns a `Time::Span` of `self` nanoseconds.
   def nanoseconds : Time::Span
     seconds = (self / Time::NANOSECONDS_PER_SECOND).to_i64