Handle relative paths in PowerShell cmdlet

IISParser.PowerShell/AsyncPSCmdlet.cs

@@ -253,16 +253,23 @@ protected ActionPreference GetErrorActionPreference() {
     /// </summary>
     /// <param name="path">The file path to check.</param>
     /// <param name="errorAction">The action preference determining error handling.</param>
+    /// <param name="resolvedPath">The resolved provider path.</param>
     /// <returns><c>true</c> if the file exists; otherwise, <c>false</c>.</returns>
-    protected bool EnsureFileExists(string path, ActionPreference errorAction) {
-        if (File.Exists(path)) {
+    protected bool EnsureFileExists(string path, ActionPreference errorAction, out string resolvedPath) {
+        try {
+            resolvedPath = GetUnresolvedProviderPathFromPSPath(path);
+        } catch (ItemNotFoundException) {
+            resolvedPath = path;
+        }
+
+        if (File.Exists(resolvedPath)) {
             return true;
         }
 
-        string message = $"{MyInvocation.InvocationName} - The specified file does not exist: {path}";
+        string message = $"{MyInvocation.InvocationName} - The specified file does not exist: {resolvedPath}";
         if (errorAction == ActionPreference.Stop) {
-            FileNotFoundException ex = new("The specified file does not exist.", path);
-            ThrowTerminatingError(new ErrorRecord(ex, "FileNotFound", ErrorCategory.ObjectNotFound, path));
+            FileNotFoundException ex = new("The specified file does not exist.", resolvedPath);
+            ThrowTerminatingError(new ErrorRecord(ex, "FileNotFound", ErrorCategory.ObjectNotFound, resolvedPath));
         } else {
             LoggingMessages.Logger.WriteWarning(message);
         }

IISParser.PowerShell/CmdletGetIISParsedLog.cs

@@ -77,13 +77,13 @@ public class CmdletGetIISParsedLog : AsyncPSCmdlet {
     public SwitchParameter Legacy { get; set; }
 
     /// <inheritdoc />
-    protected override Task BeginProcessingAsync() {
-        ActionPreference pref = GetErrorActionPreference();
-        if (EnsureFileExists(FilePath, pref)) {
-            _parser = new ParserEngine(FilePath);
-        }
-        return Task.CompletedTask;
-    }
+    protected override Task BeginProcessingAsync() {
+        ActionPreference pref = GetErrorActionPreference();
+        if (EnsureFileExists(FilePath, pref, out string resolvedPath)) {
+            _parser = new ParserEngine(resolvedPath);
+        }
+        return Task.CompletedTask;
+    }
 
     /// <inheritdoc />
     protected override Task ProcessRecordAsync() {

IISParser.Tests/ParserEngineTests.cs

@@ -19,6 +19,20 @@ public void ParseLog_ReturnsRecords() {
         Assert.Equal("192.168.0.1", record.Fields["X-Forwarded-For"]);
     }
 
+    [Fact]
+    public void ParseLog_SupportsRelativePath() {
+        var baseDir = Path.Combine(AppContext.BaseDirectory, "TestData");
+        var previous = Environment.CurrentDirectory;
+        try {
+            Environment.CurrentDirectory = baseDir;
+            var engine = new ParserEngine("./sample.log");
+            var record = engine.ParseLog().Single();
+            Assert.Equal("/index.html", record.UriPath);
+        } finally {
+            Environment.CurrentDirectory = previous;
+        }
+    }
+
     [Fact]
     public void ParseLog_RemovesKnownFieldsFromDictionary() {
         var path = Path.Combine(AppContext.BaseDirectory, "TestData", "sample.log");

Module/Examples/GetLogsRelative.ps1

@@ -0,0 +1,6 @@
+Import-Module $PSScriptRoot\..\IISParser.psd1 -Force
+
+$logDir = Join-Path $PSScriptRoot '..\..\IISParser.Tests\TestData'
+Push-Location $logDir
+Get-IISParsedLog -FilePath '.\sample.log' -First 1 | Format-Table
+Pop-Location

Module/Tests/Get-IISParsedLog.Tests.ps1

@@ -25,6 +25,17 @@ Describe 'Get-IISParsedLog' {
         ($result.PSObject.Properties.Match('Fields').Count) | Should -Be 0
     }
 
+    It 'accepts relative file paths' {
+        $logPath = (Resolve-Path "$PSScriptRoot/../../IISParser.Tests/TestData/sample.log").Path
+        Push-Location (Split-Path $logPath)
+        try {
+            $result = Get-IISParsedLog -FilePath './sample.log'
+            $result.UriPath | Should -Be '/index.html'
+        } finally {
+            Pop-Location
+        }
+    }
+
     It 'streams large log with Skip, First and Last' {
         $logPath = Join-Path $TestDrive 'large.log'
         $header = '#Fields: date time s-ip cs-method cs-uri-stem sc-status X-Forwarded-For'