Test for bug report #41397

tests/webtbs/tw41397.pp

@@ -0,0 +1,44 @@
+program Project1;
+
+{$mode objfpc}{$H+}
+
+uses
+  SysUtils;
+
+function TryEncodeDate(Year, Month, Day: Word; out Date: TDateTime): Boolean;
+var
+  I: Integer;
+  DayTable: PDayTable;
+begin
+  Result := False;
+  DayTable := @MonthDays[IsLeapYear(Year)];
+  if (Year >= 1) and (Year <= 9999) and (Month >= 1) and (Month <= 12) and
+    (Day >= 1) and (Day <= DayTable^[Month]) then
+  begin
+    for I := 1 to Month - 1 do Inc(Day, DayTable^[I]);
+    I := Year - 1;
+    // I * 365 + I div 4 - I div 100 + I div 400 + Day - DateDelta;
+    //  = 2024 * 365 + 2024 div 4 - 2024 div 100 + 2024 div 400 + 244 - 693594
+    //  = 738760     + 506        - 20           + 5            + 244 - 693594
+    //  = 45901
+    // 45901 is correct, but get 45900
+    Date := I * 365 + I div 4 - I div 100 + I div 400 + Day - DateDelta;
+    Writeln('   It should output here: 4.5901000000000000E+004');
+    Writeln('But the actual output is:', Date);
+    Result := abs(Date-45901)<0.1;
+  end;
+end;
+
+var
+  LDateTime: TDateTime;
+  res : boolean;
+begin
+  res:=TryEncodeDate(2025, 09, 01, LDateTime);
+  Writeln('TryEncodeDate:', DateTimeToStr(LDateTime));
+  if not res then
+    begin
+      Writeln('Problem detected');
+      Halt(1);
+    end;
+end.
+