Add tests for fib function

utils/coreutils.go

@@ -479,11 +479,11 @@ func copyFile(rc io.ReadCloser, path string, fm os.FileMode) (err error) {
 	return
 }
 
-// Fib returns successive Fibonacci numbers
+// Fib returns successive Fibonacci numbers.
 func Fib() func() int {
 	a, b := 0, 1
 	return func() int {
-		if b > 0 {
+		if b > 0 { // only increment Fibonacci numbers while b doesn't overflow
 			a, b = b, a+b
 		}
 		return a

utils/coreutils_test.go

@@ -1860,3 +1860,28 @@ func TestCoreUtilsSplitPath(t *testing.T) {
 		t.Errorf("expected: <%+v>, \nreceived: <%+v>", exp, rcv)
 	}
 }
+
+func TestCoreUtilsFibSeqNrOverflow(t *testing.T) {
+	fib := Fib()
+	for i := 0; i < 92; i++ { // the 93rd fibonacci number in the sequence would normally overflow
+		fib()
+	}
+	exp := fib()
+	for i := 0; i < 100; i++ {
+		if rcv := fib(); rcv != exp {
+			t.Errorf("expected: <%+v>, \nreceived: <%+v>", exp, rcv)
+		}
+	}
+}
+
+func TestCoreUtilsFibDurationSeqNrOverflow(t *testing.T) {
+	fib := FibDuration(time.Second, 0)
+	for i := 0; i < 49; i++ { // the 50th fibonacci number in the sequence would normally overflow when multiplied with time.Second
+		fib()
+	}
+	for i := 0; i < 100; i++ {
+		if rcv := fib(); rcv != AbsoluteMaxDuration {
+			t.Errorf("expected: <%+v>, \nreceived: <%+v>", AbsoluteMaxDuration, rcv)
+		}
+	}
+}