Add Fix switch parameter for 'File' parameter set to auto-correct warnings (#802)

Engine/Commands/InvokeScriptAnalyzerCommand.cs

@@ -180,6 +180,17 @@ public SwitchParameter SuppressedOnly
         }
         private bool suppressedOnly;
 
+        /// <summary>
+        /// Resolves rule violations automatically where possible.
+        /// </summary>
+        [Parameter(Mandatory = false, ParameterSetName = "File")]
+        public SwitchParameter Fix
+        {
+            get { return fix; }
+            set { fix = value; }
+        }
+        private bool fix;
+
         /// <summary>
         /// Returns path to the file that contains user profile or hash table for ScriptAnalyzer
         /// </summary>
@@ -377,7 +388,7 @@ private void ProcessInput()
             {
                 foreach (var p in processedPaths)
                 {
-                    diagnosticsList = ScriptAnalyzer.Instance.AnalyzePath(p, this.recurse);
+                    diagnosticsList = ScriptAnalyzer.Instance.AnalyzePath(p, this.recurse, this.fix);
                     WriteToOutput(diagnosticsList);
                 }
             }

Engine/ScriptAnalyzer.cs

@@ -31,6 +31,7 @@
 using System.Collections.ObjectModel;
 using System.Collections;
 using System.Diagnostics;
+using System.Text;
 
 namespace Microsoft.Windows.PowerShell.ScriptAnalyzer
 {
@@ -1451,11 +1452,12 @@ public Dictionary<string, List<string>> CheckRuleExtension(string[] path, PathIn
         /// </summary>
         /// <param name="path">The path of the file or directory to analyze.</param>
         /// <param name="searchRecursively">
+        /// <param name="fix">
         /// If true, recursively searches the given file path and analyzes any
         /// script files that are found.
         /// </param>
         /// <returns>An enumeration of DiagnosticRecords that were found by rules.</returns>
-        public IEnumerable<DiagnosticRecord> AnalyzePath(string path, bool searchRecursively = false)
+        public IEnumerable<DiagnosticRecord> AnalyzePath(string path, bool searchRecursively = false, bool fix = false)
         {
             List<string> scriptFilePaths = new List<string>();
 
@@ -1475,6 +1477,13 @@ public IEnumerable<DiagnosticRecord> AnalyzePath(string path, bool searchRecursi
             this.BuildScriptPathList(path, searchRecursively, scriptFilePaths);
             foreach (string scriptFilePath in scriptFilePaths)
             {
+                if (fix)
+                {
+                    var fileEncoding = GetFileEncoding(scriptFilePath);
+                    var scriptFileContentWithFixes = Fix(File.ReadAllText(scriptFilePath, fileEncoding));
+                    File.WriteAllText(scriptFilePath, scriptFileContentWithFixes, fileEncoding);   // although this preserves the encoding, it will add a BOM to UTF8 files
+                }
+
                 // Yield each record in the result so that the
                 // caller can pull them one at a time
                 foreach (var diagnosticRecord in this.AnalyzeFile(scriptFilePath))
@@ -1613,6 +1622,18 @@ public EditableText Fix(EditableText text, Range range, out Range updatedRange)
             return text;
         }
 
+        private static Encoding GetFileEncoding(string path)
+        {
+            using (var stream = new FileStream(path, FileMode.Open))
+            {
+                using (var reader = new StreamReader(stream))
+                {
+                    reader.Peek(); // needed in order to populate the CurrentEncoding property
+                    return reader.CurrentEncoding;
+                }
+            }
+        }
+
         private static Range SnapToEdges(EditableText text, Range range)
         {
             // todo add TextLines.Validate(range) and TextLines.Validate(position)

docs/markdown/Invoke-ScriptAnalyzer.md

@@ -12,7 +12,7 @@ Evaluates a script or module based on selected best practice rules
 ### UNNAMED_PARAMETER_SET_1
 ```
 Invoke-ScriptAnalyzer [-Path] <String> [-CustomRulePath <String>] [-RecurseCustomRulePath]
- [-ExcludeRule <String[]>] [-IncludeRule <String[]>] [-Severity <String[]>] [-Recurse] [-SuppressedOnly]
+ [-ExcludeRule <String[]>] [-IncludeRule <String[]>] [-Severity <String[]>] [-Recurse] [-SuppressedOnly] [-Fix]
  [-Settings <String>]
 ```
 
@@ -399,6 +399,23 @@ Accept pipeline input: False
 Accept wildcard characters: False
 ```
 
+### -Fix
+Certain warnings contain a suggested fix in their DiagnosticRecord and therefore those warnings will be fixed automatically using this fix.
+
+When you used Fix, Invoke-ScriptAnalyzer runs as usual but will apply the fixes before running the analysis. Please make sure that you have a backup of your files when using this switch. It tries to pre-server the file encoding but it is possible that a BOM gets added to the fixed files.
+
+```yaml
+Type: SwitchParameter
+Parameter Sets: UNNAMED_PARAMETER_SET_1
+Aliases:
+
+Required: False
+Position: Named
+Default value: False
+Accept pipeline input: False
+Accept wildcard characters: False
+```
+
 ### -Settings
 File path that contains user profile or hash table for ScriptAnalyzer