diff --git a/units/duration_test.go b/units/duration_test.go
new file mode 100644
index 0000000..4906f8a
--- /dev/null
+++ b/units/duration_test.go
@@ -0,0 +1,52 @@
+package units
+
+import (
+	"testing"
+	"time"
+)
+
+func TestHumanDuration(t *testing.T) {
+	// Useful duration abstractions
+	day := 24 * time.Hour
+	week := 7 * day
+	month := 30 * day
+	year := 365 * day
+
+	assertEquals(t, "Less than a second", HumanDuration(450*time.Millisecond))
+	assertEquals(t, "47 seconds", HumanDuration(47*time.Second))
+	assertEquals(t, "About a minute", HumanDuration(1*time.Minute))
+	assertEquals(t, "3 minutes", HumanDuration(3*time.Minute))
+	assertEquals(t, "35 minutes", HumanDuration(35*time.Minute))
+	assertEquals(t, "35 minutes", HumanDuration(35*time.Minute+40*time.Second))
+	assertEquals(t, "About an hour", HumanDuration(1*time.Hour))
+	assertEquals(t, "About an hour", HumanDuration(1*time.Hour+45*time.Minute))
+	assertEquals(t, "3 hours", HumanDuration(3*time.Hour))
+	assertEquals(t, "3 hours", HumanDuration(3*time.Hour+59*time.Minute))
+	assertEquals(t, "4 hours", HumanDuration(3*time.Hour+60*time.Minute))
+	assertEquals(t, "24 hours", HumanDuration(24*time.Hour))
+	assertEquals(t, "36 hours", HumanDuration(1*day+12*time.Hour))
+	assertEquals(t, "2 days", HumanDuration(2*day))
+	assertEquals(t, "7 days", HumanDuration(7*day))
+	assertEquals(t, "13 days", HumanDuration(13*day+5*time.Hour))
+	assertEquals(t, "2 weeks", HumanDuration(2*week))
+	assertEquals(t, "2 weeks", HumanDuration(2*week+4*day))
+	assertEquals(t, "3 weeks", HumanDuration(3*week))
+	assertEquals(t, "4 weeks", HumanDuration(4*week))
+	assertEquals(t, "4 weeks", HumanDuration(4*week+3*day))
+	assertEquals(t, "4 weeks", HumanDuration(1*month))
+	assertEquals(t, "6 weeks", HumanDuration(1*month+2*week))
+	assertEquals(t, "8 weeks", HumanDuration(2*month))
+	assertEquals(t, "3 months", HumanDuration(3*month+1*week))
+	assertEquals(t, "5 months", HumanDuration(5*month+2*week))
+	assertEquals(t, "13 months", HumanDuration(13*month))
+	assertEquals(t, "23 months", HumanDuration(23*month))
+	assertEquals(t, "24 months", HumanDuration(24*month))
+	assertEquals(t, "2.010959 years", HumanDuration(24*month+2*week))
+	assertEquals(t, "3.164384 years", HumanDuration(3*year+2*month))
+}
+
+func assertEquals(t *testing.T, expected, actual interface{}) {
+	if expected != actual {
+		t.Errorf("Expected '%s' but got '%s'", expected, actual)
+	}
+}
diff --git a/units/size_test.go b/units/size_test.go
index 2c4982b..de8b44f 100644
--- a/units/size_test.go
+++ b/units/size_test.go
@@ -1,23 +1,20 @@
 package units
 
 import (
-	"strings"
 	"testing"
 )
 
 func TestHumanSize(t *testing.T) {
-
-	size := strings.Trim(HumanSize(1000), " \t")
-	expect := "1 kB"
-	if size != expect {
-		t.Errorf("1000 -> expected '%s', got '%s'", expect, size)
-	}
-
-	size = strings.Trim(HumanSize(1024), " \t")
-	expect = "1.024 kB"
-	if size != expect {
-		t.Errorf("1024 -> expected '%s', got '%s'", expect, size)
-	}
+	assertEquals(t, "1 kB", HumanSize(1000))
+	assertEquals(t, "1.024 kB", HumanSize(1024))
+	assertEquals(t, "1 MB", HumanSize(1000000))
+	assertEquals(t, "1.049 MB", HumanSize(1048576))
+	assertEquals(t, "2 MB", HumanSize(2*1000*1000))
+	assertEquals(t, "3.42 GB", HumanSize(3.42*1000*1000*1000))
+	assertEquals(t, "5.372 TB", HumanSize(5.372*1000*1000*1000*1000))
+	assertEquals(t, "2.22 PB", HumanSize(2.22*1000*1000*1000*1000*1000))
+	assertEquals(t, "2.22 EB", HumanSize(2.22*1000*1000*1000*1000*1000*1000))
+	assertEquals(t, "7.707 EB", HumanSize(7.707*1000*1000*1000*1000*1000*1000))
 }
 
 func TestFromHumanSize(t *testing.T) {