Enhance file path handling in DbfDbCommand and add tests for filename variations (#264)

* Enhance file path handling in DbfDbCommand and add tests for filename variations

* Improve error message for invalid command text and enhance filename parsing tests

Author: chrisrichards

src/DbfDataReader/DbfDbCommand.cs

@@ -61,14 +61,33 @@ protected override DbDataReader ExecuteDbDataReader(CommandBehavior behavior)
             }
 
             var fileName = QueryParser.Parse(CommandText);
+            var filePath = GetFilePath(folder, fileName);
+
+            var options = dbfDbConnection.Options;
+            return new DbfDataReader(filePath, options);
+        }
+
+        private static string GetFilePath(string folder, string fileName)
+        {
             var filePath = Path.Combine(folder, $"{fileName}");
-            if (!File.Exists(filePath))
+            if (File.Exists(filePath))
+            {
+                return filePath;
+            }
+            
+            filePath = Path.ChangeExtension(filePath, ".dbf");
+            if (File.Exists(filePath))
             {
-                throw new FileNotFoundException(filePath);
+                return filePath;
             }
 
-            var options = dbfDbConnection.Options;
-            return new DbfDataReader(filePath, options);
+            filePath = Path.ChangeExtension(filePath, ".DBF");
+            if (File.Exists(filePath))
+            {
+                return filePath;
+            }
+
+            throw new FileNotFoundException(filePath);
         }
     }
 }

src/DbfDataReader/QueryParser.cs

@@ -23,7 +23,7 @@ internal static string Parse(string commandText)
             var match = FileNameRegex.Match(commandText);
             if (!match.Success)
             {
-                throw new ArgumentException("The command text must be in the format 'SELECT * FROM <FILENAME>'.", nameof(commandText));
+                throw new ArgumentException($"Invalid command text: '{commandText}'. Must be in the format 'SELECT * FROM <FILENAME>'.", nameof(commandText));
             }
 
             return match.Groups["FileName"].Value;

test/DbfDataReader.Tests/DbfDbConnectionTests.cs

@@ -53,5 +53,31 @@ public async Task Should_skip_deleted_rows()
         }
 
         rowCount.ShouldBe(12);
+    }
+    
+    [Theory]
+    [InlineData("dbase_03")]
+    [InlineData("dbase_03.dbf")]
+    [InlineData("dbase_03.DBF")]
+    public async Task Should_read_file(string filename)
+    {
+        var dbConnection = new DbfDbConnection();
+        dbConnection.ConnectionString = $"Folder={FolderPath};Encoding=ascii;SkipDeletedRecords=false";
+        dbConnection.Open();
+        
+        var dbCommand = dbConnection.CreateCommand();
+        dbCommand.CommandText = $"select * from {filename};";
+
+        var rowCount = 0;
+        var reader = await dbCommand.ExecuteReaderAsync();
+        while (await reader.ReadAsync())
+        {
+            rowCount++;
+
+            _ = reader.GetString(0);
+            _ = reader.GetDecimal(10);
+        }
+
+        rowCount.ShouldBe(14);
     }    
 }

test/DbfDataReader.Tests/QueryParserTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using Bogus;
 using Shouldly;
 using Xunit;
@@ -7,49 +8,65 @@ namespace DbfDataReader.Tests;
 
 public class QueryParserTests
 {
+    private readonly string _fileName;
+    public QueryParserTests()
+    {
+        var faker = new Faker();
+        var fileName = faker.System.FileName("dbf");
+        _fileName = fileName.Replace("&", "_and_");
+    }
+    
+    [Fact]
+    public void Should_parse_filename_without_extension()
+    {
+        // Arrange
+        var fileNameWithoutExtension = Path.GetFileNameWithoutExtension(_fileName);
+        var query = $"select * from {fileNameWithoutExtension}";
+        
+        // Act
+        var result = QueryParser.Parse(query);
+        
+        // Assert
+        result.ShouldBe(fileNameWithoutExtension);
+    }
+
     [Fact]
     public void Should_parse_lowercase_query()
     {
         // Arrange
-        var faker = new Faker();
-        var fileName = $"{faker.System.FileName()}.dbf";
-        var query = $"select * from {fileName}";
+        var query = $"select * from {_fileName}";
 
         // Act
         var result = QueryParser.Parse(query);
 
         // Assert
-        result.ShouldBe(fileName);
+        result.ShouldBe(_fileName);
     }
 
     [Fact]
     public void Should_parse_uppercase_query()
     {
         // Arrange
-        var faker = new Faker();
-        var fileName = $"{faker.System.FileName()}.dbf".ToUpper();
-        var query = $"SELECT * FROM {fileName}";
+        var query = $"SELECT * FROM {_fileName}";
 
         // Act
         var result = QueryParser.Parse(query);
 
         // Assert
-        result.ShouldBe(fileName);
+        result.ShouldBe(_fileName);
     }
 
     [Fact]
     public void Should_parse_mixed_case_query()
     {
         // Arrange
-        var faker = new Faker();
-        var fileName = $"{faker.System.FileName()}.dbf";
-        var query = $"SELECT * from {fileName}";
+        var query = $"SELECT * from {_fileName}";
 
         // Act
         var result = QueryParser.Parse(query);
 
         // Assert
-        result.ShouldBe(fileName);
+        result.ShouldBe(_fileName);
     }
 
     [Fact]