Improved test coverage and argument validation in: SingleStepSolution, SudokuPuzzle and SudokuFilePuzzleProvider classes.

Author: kurtanr

SimpleSudokuSolver.Tests/PuzzleProviders/SudokuFilePuzzleProviderTests.cs

@@ -17,9 +17,11 @@ public void SudokuFilePuzzleProvider_ThrowsExceptionForEmptyPath_Test()
     }
 
     [Test]
-    public void SudokuFilePuzzleProvider_WorksWithAllFormats_Test()
+    public void SudokuFilePuzzleProvider_IgnoresCommentsAndEmptyLines_WorksWithAllFormats_Test()
     {
       var filePath = Path.GetTempFileName();
+      File.WriteAllText(filePath, $"#comment{Environment.NewLine} #comment{Environment.NewLine} {Environment.NewLine}");
+
       var separators = new[] { ",", " ", "\t", "" };
       var sudoku = new int[9, 9];
       sudoku[1, 2] = 5;
@@ -39,7 +41,7 @@ private void SaveSudokuUsingSeparator(int[,] sudoku, string separator, string fi
     {
       var sudokuToString = new SudokuPuzzle(sudoku).ToString();
       var sudokuToStringWithSeparator = sudokuToString.Replace(" ", separator);
-      File.WriteAllText(filePath, sudokuToStringWithSeparator);
+      File.AppendAllText(filePath, sudokuToStringWithSeparator);
     }
   }
 }

SimpleSudokuSolver.Tests/SingleStepSolutionTests.cs

@@ -6,6 +6,18 @@ namespace SimpleSudokuSolver.Tests
   [TestFixture]
   public class SingleStepSolutionTests
   {
+    [Test]
+    public void ConstructorArgumentValidationTest()
+    {
+      var eliminations = new SingleStepSolution.Candidate[0];
+      Assert.That(() => new SingleStepSolution(null, "test"), Throws.InstanceOf<ArgumentNullException>());
+      Assert.That(() => new SingleStepSolution(eliminations, null), Throws.InstanceOf<ArgumentNullException>());
+      Assert.That(() => new SingleStepSolution(eliminations, string.Empty), Throws.InstanceOf<ArgumentException>());
+
+      Assert.That(() => new SingleStepSolution(0, 0, 0, null), Throws.InstanceOf<ArgumentNullException>());
+      Assert.That(() => new SingleStepSolution(0, 0, 0, string.Empty), Throws.InstanceOf<ArgumentException>());
+    }
+
     [Test]
     public void CandidateEqualityTest()
     {

SimpleSudokuSolver/Model/SudokuPuzzle.cs

@@ -79,8 +79,7 @@ public void ApplySingleStepSolution(SingleStepSolution singleStepSolution)
       if (singleStepSolution == null)
         return;
 
-      if (singleStepSolution.Result == null &&
-        (singleStepSolution.Eliminations == null || singleStepSolution.Eliminations.Length == 0))
+      if (singleStepSolution.Result == null && singleStepSolution.Eliminations.Length == 0)
         return;
 
       int[] oldCanBe = new int[] { };

SimpleSudokuSolver/SingleStepSolution.cs

@@ -115,6 +115,8 @@ public override string ToString()
 
     public SingleStepSolution(int indexOfRow, int indexOfColumn, int value, string strategyName)
     {
+      ValidateStrategyName(strategyName);
+
       Eliminations = null;
       Result = new Candidate(indexOfRow, indexOfColumn, value);
       Strategy = strategyName;
@@ -123,6 +125,11 @@ public SingleStepSolution(int indexOfRow, int indexOfColumn, int value, string s
 
     public SingleStepSolution(Candidate[] eliminations, string strategyName)
     {
+      if (eliminations == null)
+        throw new ArgumentNullException(nameof(eliminations));
+
+      ValidateStrategyName(strategyName);
+
       Eliminations = eliminations;
       Result = null;
 
@@ -132,7 +139,7 @@ public SingleStepSolution(Candidate[] eliminations, string strategyName)
       var stringBuilder = new StringBuilder();
       stringBuilder.AppendLine($"Eliminated candidates [{strategyName}]:");
 
-      foreach(var groupedElimination in groupedEliminations)
+      foreach (var groupedElimination in groupedEliminations)
       {
         stringBuilder.AppendLine($"- Row {groupedElimination.IndexOfRow + 1} Column {groupedElimination.IndexOfColumn + 1} " +
           $"Values {string.Join(",", groupedElimination.Values)}");
@@ -146,5 +153,14 @@ public override string ToString()
     {
       return SolutionDescription;
     }
+
+    private void ValidateStrategyName(string strategyName)
+    {
+      if (strategyName == null)
+        throw new ArgumentNullException(nameof(strategyName));
+
+      if (string.IsNullOrEmpty(strategyName))
+        throw new ArgumentException("Must not be an empty string", nameof(strategyName));
+    }
   }
 }