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{$M+} // DUnitX would add it anyway
unit TestDECRandom;

interface

// Needs to be included before any other statements
{$INCLUDE TestDefines.inc}

uses
  System.SysUtils, System.Classes,
  {$IFDEF DUnitX}
  DUnitX.TestFramework,DUnitX.DUnitCompatibility,
  {$ELSE}
  TestFramework,
  {$ENDIF}
  DECRandom;

type
  /// <summary>
  ///   This can only implement a rough test of the default behavior of the PNRG.
  ///   We do not have access to the default seed value generation functions etc.
  ///   so we cannod test RandomSeed properly as we could provide our own
  ///   implementation of the default seed generators but couldn't resore the
  ///   default ones afterwards, which should be done to enable repeated test
  ///   runs in the same session.
  /// </summary>
  TTestRandom = class(TTestCase)
  private
    RandomNumbers: TBytes;
  public
  published
    procedure TestRandomLong;
    procedure TestRandomBytes;
    procedure TestRandomBuffer;
    procedure TestRandomBufferIncompletelyFilled;
  end;

implementation

{ TTestRandom }

procedure TTestRandom.TestRandomBuffer;
var
  Result : TBytes;
  Expected : TBytes;
  i : Integer;
begin
  // Set up the seed with a known value of 0 so always the same known sequence
  // results
  RandomSeed(RandomNumbers, 0);
  SetLength(Result, 5);
  FillChar(Result[0], 5, 0);

  RandomBuffer(Result[0], 5);

  Expected := TBytes.Create(208, 208, 25, 65, 118);

  for i := Low(Expected) to High(Expected) do
    CheckEquals(Expected[i], Result[i],
                'Wrong random number in known sequence at index ' + IntToStr(i));

  SetLength(Result, 5);
  FillChar(Result[0], 5, 0);

  RandomBuffer(Result[0], 5);

  Expected := TBytes.Create(107, 181, 127, 194, 179);

  for i := Low(Expected) to High(Expected) do
    CheckEquals(Expected[i], Result[i],
                'Wrong random number in known sequence at index ' + IntToStr(i));
end;

procedure TTestRandom.TestRandomBufferIncompletelyFilled;
var
  Result : TBytes;
  Expected : TBytes;
  i : Integer;
begin
  // Set up the seed with a known value of 0 so always the same known sequence
  // results
  RandomSeed(RandomNumbers, 0);
  SetLength(Result, 10);
  FillChar(Result[0], 5, 0);

  RandomBuffer(Result[0], 5);

  Expected := TBytes.Create(208, 208, 25, 65, 118, 0, 0, 0, 0, 0);

  for i := Low(Expected) to High(Expected) do
    CheckEquals(Expected[i], Result[i],
                'Wrong random number in known sequence at index ' + IntToStr(i));

  SetLength(Result, 10);
  FillChar(Result[0], 5, 0);

  RandomBuffer(Result[0], 5);

  Expected := TBytes.Create(107, 181, 127, 194, 179, 0, 0, 0, 0, 0);

  for i := Low(Expected) to High(Expected) do
    CheckEquals(Expected[i], Result[i],
                'Wrong random number in known sequence at index ' + IntToStr(i));
end;

procedure TTestRandom.TestRandomBytes;
var
  Result : TBytes;
  Expected : TBytes;
  i : Integer;
begin
  // Set up the seed with a known value of 0 so always the same known sequence
  // results
  RandomSeed(RandomNumbers, 0);
  Result := RandomBytes(5);

  Expected := TBytes.Create(208, 208, 25, 65, 118);

  for i := Low(Expected) to High(Expected) do
    CheckEquals(Expected[i], Result[i],
                'Wrong random number in known sequence at index ' + IntToStr(i));

  Result := RandomBytes(5);

  Expected := TBytes.Create(107, 181, 127, 194, 179);

  for i := Low(Expected) to High(Expected) do
    CheckEquals(Expected[i], Result[i],
                'Wrong random number in known sequence at index ' + IntToStr(i));
end;

procedure TTestRandom.TestRandomLong;
begin
  // Set up the seed with a known value of 0 so always the same known sequence
  // results
  RandomSeed(RandomNumbers, 0);
  CheckEquals(1092210896, RandomLong, 'Wrong random number from known sequence');
  CheckEquals(2142595958, RandomLong, 'Wrong random number from known sequence');
  CheckEquals(1475261378, RandomLong, 'Wrong random number from known sequence');
end;

initialization
  // Register any test cases with the test runner
  {$IFDEF DUnitX}
  TDUnitX.RegisterTestFixture(TTestRandom);
  {$ELSE}
  RegisterTests('DECRandom', [TTestRandom.Suite]);
  {$ENDIF}
end.