Option VBASupport 1 Option Explicit Dim passCount As Integer Dim failCount As Integer Dim result As String Function doUnitTest() As String result = verify_testDateAdd() If failCount <> 0 Or passCount = 0 Then doUnitTest = result Else doUnitTest = "OK" End If End Function Function verify_testDateAdd() As String passCount = 0 failCount = 0 result = "Test Results" & Chr$(10) & "============" & Chr$(10) Dim testName As String Dim date1, date2 As Date 'variables for test testName = "Test DateAdd function" On Error GoTo errorHandler date2 = CDate("1995-02-28") date1 = DateAdd("m", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-02-28") date1 = DateAdd("m", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-02-28") date1 = DateAdd("m", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1996-01-31") date1 = DateAdd("yyyy", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-04-30") date1 = DateAdd("q", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-02-01") date1 = DateAdd("y", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-02-01") date1 = DateAdd("d", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-02-01") date1 = DateAdd("w", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-02-07") date1 = DateAdd("ww", 1, "1995-01-31") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 Rem This fails when directly comparing date1=date2, probably due to rounding. Rem Workaround convert to string which does the rounding. Dim date1s, date2s As String date2 = CDate("1995-01-01 22:48:29") date1 = DateAdd("h", 1, "1995-01-01 21:48:29") date1s = "" & date1 date2s = "" & date2 TestLog_ASSERT date1s = date2s, "the return DateAdd is: " & date1 date2 = CDate("1995-01-31 21:49:29") date1 = DateAdd("n", 1, "1995-01-31 21:48:29") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 date2 = CDate("1995-01-31 21:48:30") date1 = DateAdd("s", 1, "1995-01-31 21:48:29") TestLog_ASSERT date1 = date2, "the return DateAdd is: " & date1 exitFunc: result = result & Chr$(10) & "Tests passed: " & passCount & Chr$(10) & "Tests failed: " & failCount & Chr$(10) verify_testDateAdd = result Exit Function errorHandler: On Error GoTo 0 TestLog_ASSERT (False), testName & ": hit error handler" GoTo exitFunc End Function Sub TestLog_ASSERT(assertion As Boolean, Optional testId As String, Optional testComment As String) If assertion = True Then passCount = passCount + 1 Else Dim testMsg As String If Not IsMissing(testId) Then testMsg = testMsg + " : " + testId End If If Not IsMissing(testComment) And Not (testComment = "") Then testMsg = testMsg + " (" + testComment + ")" End If result = result & Chr$(10) & " Failed: " & testMsg failCount = failCount + 1 End If End Sub