{
  Solutions to the Advent Of Code.
  Copyright (C) 2024  Stefan Müller

  This program is free software: you can redistribute it and/or modify it under
  the terms of the GNU General Public License as published by the Free Software
  Foundation, either version 3 of the License, or (at your option) any later
  version.

  This program is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License along with
  this program.  If not, see <http://www.gnu.org/licenses/>.
}

unit UBinomialCoefficientsTestCases;

{$mode ObjFPC}{$H+}

interface

uses
  Classes, SysUtils, fpcunit, testregistry, UBinomialCoefficients;

type

  { TBinomialCoefficientsTestCase }

  TBinomialCoefficientsTestCase = class(TTestCase)
  private
    FBinomialCoefficientCache: TBinomialCoefficientCache;
    procedure RunRangeError;
    procedure AssertEqualsCalculation(const AN, AK, AExpected: Cardinal);
    procedure AssertEqualsCachedRowsCount(const AExpected: Cardinal);
  protected
    procedure SetUp; override;
    procedure TearDown; override;
  published
    procedure TestZeroChooseZero;
    procedure TestNChooseZero;
    procedure TestNChooseN;
    procedure TestNChooseK;
    procedure TestCombined;
    procedure TestFullRow;
    procedure TestRangeError;
  end;

  { TBinomialCoefficientsGlobalTestCase }

  TBinomialCoefficientsGlobalTestCase = class(TTestCase)
  private
    procedure AssertEqualsCalculation(const AN, AK, AExpected: Cardinal);
  published
    procedure TestCombined;
  end;

implementation

{ TBinomialCoefficientsTestCase }

procedure TBinomialCoefficientsTestCase.RunRangeError;
begin
  FBinomialCoefficientCache.Get(1, 5);
end;

procedure TBinomialCoefficientsTestCase.AssertEqualsCalculation(const AN, AK, AExpected: Cardinal);
begin
  AssertEquals('Unexpected calculation result', AExpected, FBinomialCoefficientCache.Get(AN, AK));
end;

procedure TBinomialCoefficientsTestCase.AssertEqualsCachedRowsCount(const AExpected: Cardinal);
begin
  AssertEquals('Unexpected cached rows count', AExpected, FBinomialCoefficientCache.GetCachedRowsCount);
end;

procedure TBinomialCoefficientsTestCase.SetUp;
begin
  FBinomialCoefficientCache := TBinomialCoefficientCache.Create;
end;

procedure TBinomialCoefficientsTestCase.TearDown;
begin
  FBinomialCoefficientCache.Free;
end;

procedure TBinomialCoefficientsTestCase.TestZeroChooseZero;
begin
  AssertEqualsCalculation(0, 0, 1);
  AssertEqualsCachedRowsCount(1);
end;

procedure TBinomialCoefficientsTestCase.TestNChooseZero;
begin
  AssertEqualsCalculation(15, 0, 1);
  AssertEqualsCachedRowsCount(16);
end;

procedure TBinomialCoefficientsTestCase.TestNChooseN;
begin
  AssertEqualsCalculation(11, 11, 1);
  AssertEqualsCachedRowsCount(12);
end;

procedure TBinomialCoefficientsTestCase.TestNChooseK;
begin
  AssertEqualsCalculation(8, 3, 56);
  AssertEqualsCachedRowsCount(9);
end;

procedure TBinomialCoefficientsTestCase.TestCombined;
begin
  AssertEqualsCalculation(5, 1, 5);
  AssertEqualsCachedRowsCount(6);
  AssertEqualsCalculation(8, 4, 70);
  AssertEqualsCachedRowsCount(9);
  AssertEqualsCalculation(3, 1, 3);
  AssertEqualsCachedRowsCount(9);
end;

procedure TBinomialCoefficientsTestCase.TestFullRow;
begin
  AssertEqualsCalculation(5, 0, 1);
  AssertEqualsCachedRowsCount(6);
  AssertEqualsCalculation(5, 1, 5);
  AssertEqualsCachedRowsCount(6);
  AssertEqualsCalculation(5, 2, 10);
  AssertEqualsCachedRowsCount(6);
  AssertEqualsCalculation(5, 3, 10);
  AssertEqualsCachedRowsCount(6);
  AssertEqualsCalculation(5, 4, 5);
  AssertEqualsCachedRowsCount(6);
  AssertEqualsCalculation(5, 5, 1);
  AssertEqualsCachedRowsCount(6);
end;

procedure TBinomialCoefficientsTestCase.TestRangeError;
begin
  AssertException(ERangeError, @RunRangeError);
end;

{ TBinomialCoefficientsGlobalTestCase }

procedure TBinomialCoefficientsGlobalTestCase.AssertEqualsCalculation(const AN, AK, AExpected: Cardinal);
begin
  AssertEquals('Unexpected calculation result', AExpected, BinomialCoefficients.Get(AN, AK));
end;

procedure TBinomialCoefficientsGlobalTestCase.TestCombined;
begin
  AssertEqualsCalculation(5, 1, 5);
  AssertEqualsCalculation(8, 4, 70);
  AssertEqualsCalculation(3, 1, 3);
end;

initialization

  RegisterTest('Helper.TBinomialCoefficientCache', TBinomialCoefficientsTestCase);
  RegisterTest('Helper.TBinomialCoefficientCache', TBinomialCoefficientsGlobalTestCase);
end.