mono/tests/exception20.cs

   1 using System;
   2 using System.Linq;
   3 using System.Runtime.CompilerServices;
   4 using System.IO;
   5
   6 class CustomException : Exception
   7 {
   8         public int Value;
   9         public CustomException (int value) => this.Value = value;
  10 }
  11
  12 class C
  13 {
  14         static CustomException e;
  15
  16         [MethodImpl(MethodImplOptions.NoInlining)]
  17         static void ThrowCustomException ()
  18         {
  19                 throw new CustomException(1);
  20         }
  21
  22         [MethodImpl(MethodImplOptions.NoInlining)]
  23         static void Throw ()
  24         {
  25                 try {
  26                         ThrowCustomException ();
  27                 } catch (CustomException ex) {
  28                         e = ex;
  29                         // so, the original exception has two frames
  30                         CheckTrace (e, 2);
  31                 }
  32         }
  33
  34         static int FrameCount (Exception ex)
  35         {
  36                         string fullTrace = ex.StackTrace;
  37                         if (fullTrace == null)
  38                                 throw new Exception ("Empty trace found!");
  39
  40                         string[] frames = fullTrace.Split(new string[] { Environment.NewLine }, StringSplitOptions.None);
  41
  42                         // Ignore metadata
  43                         frames = frames.Where (l => !l.StartsWith ("[")).ToArray ();
  44
  45                         return frames.Length;
  46         }
  47
  48         // throws on false anyway
  49         [MethodImpl(MethodImplOptions.NoInlining)]
  50         static bool CheckTrace (Exception ex, int numFramesToExpect, bool whatToReturn = true)
  51         {
  52                 int frames = FrameCount (ex);
  53                 if (frames != numFramesToExpect) {
  54                         throw new Exception ($"Exception carried {frames} frames along with it when it should have reported {numFramesToExpect}. Full trace:\n---\n{ex.StackTrace}\n---");
  55                 }
  56
  57                 return whatToReturn;
  58         }
  59
  60         [MethodImpl(MethodImplOptions.NoInlining)]
  61         static void ThrowCustomExceptionWithValueButFailsToCatchWithFilter ()
  62         {
  63                 try {
  64                         ThrowCustomException (1);
  65                 } catch (CustomException ce) when (ce.Value == 9999) {
  66                         throw new Exception ("This should NEVER be hit");
  67                 }
  68         }
  69
  70         [MethodImpl(MethodImplOptions.NoInlining)]
  71         static void ThrowCustomException (int value)
  72         {
  73                 throw new CustomException (value);
  74         }
  75
  76         [MethodImpl(MethodImplOptions.NoInlining)]
  77         static void ThrowFileNotFoundException ()
  78         {
  79                 throw new FileNotFoundException ();
  80         }
  81
  82         public static void Main ()
  83         {
  84                 Throw ();
  85
  86                 // Single frame
  87                 // Filter returns false
  88                 // Original exception @e had two frames, but after throwing here it
  89                 // should have just 1
  90                 try {
  91                         throw e;
  92                 } catch (Exception ex) when (CheckTrace (ex, 1, true)) {
  93                         CheckTrace (ex, 1);
  94                 }
  95
  96                 // Throw + filter fails, then filter matches at next level
  97                 try {
  98                         ThrowCustomExceptionWithValueButFailsToCatchWithFilter ();
  99                 } catch (CustomException ex) when (CheckTrace (ex, 3, true)) {
 100                         CheckTrace (ex, 3);
 101                 }
 102
 103                 // Throw + filter fails, then filter matches, exception re-thrown and caught
 104                 try {
 105                         try {
 106                                 ThrowCustomExceptionWithValueButFailsToCatchWithFilter ();
 107                         } catch (CustomException ex) when (CheckTrace (ex, 3, true)) {
 108                                 CheckTrace (ex, 3);
 109
 110                                 // this will truncate the trace now
 111                                 throw ex;
 112                         }
 113                 } catch (Exception ex) {
 114                         CheckTrace (ex, 1);
 115                 }
 116
 117                 // Throw, filter matches, throw exception as-is, caught
 118                 try {
 119                         try {
 120                                 ThrowFileNotFoundException ();
 121                         } catch (Exception e) when (CheckTrace (e, 2)) {
 122                                 // trace should remain as is
 123                                 throw;
 124                         }
 125                 } catch (Exception ex) {
 126                         CheckTrace (ex, 2);
 127                 }
 128         }
 129 }