A minimum tactical fix for issue #697 (#698)

* Provoke the issue

* Minimum fix

(cherry picked from commit 0f23047c62027e10206a5d0dbb81cba6f2dc260f)

* Revert "Provoke the issue"

This reverts commit 1a2275b7f6704298fa386fa416c91bb09f0368bf.

* Add unit test

(cherry picked from commit 185ba884111e30cfb84aeb64f00324d995cfdd35)

* Use existing infrastructure

* Quick fix

Co-authored-by: Jb Evain <jb@evain.net>

3 files changed, 23 insertions, 0 deletions

diff --git a/Test/Mono.Cecil.Tests/ILProcessorTests.cs b/Test/Mono.Cecil.Tests/ILProcessorTests.cs
index 8836615..4eecfe3 100644
--- a/Test/Mono.Cecil.Tests/ILProcessorTests.cs
+++ b/Test/Mono.Cecil.Tests/ILProcessorTests.cs
@@ -5,6 +5,7 @@ using System.Linq;
 
 using Mono.Cecil;
 using Mono.Cecil.Cil;
+using Mono.Cecil.Mdb;
 using Mono.Cecil.Pdb;
 using NUnit.Framework;
 
@@ -41,6 +42,28 @@ namespace Mono.Cecil.Tests {
 		}
 
 		[Test]
+		public void InsertBeforeIssue697 ()
+		{
+			var parameters = new ReaderParameters { SymbolReaderProvider = new MdbReaderProvider () };
+			using (var module = GetResourceModule ("Issue697.dll", parameters))
+			{
+				var pathGetterDef = module.GetTypes ()
+					.SelectMany (t => t.Methods)
+					.First (m => m.Name.Equals ("get_Defer"));
+
+				var body = pathGetterDef.Body;
+				var worker = body.GetILProcessor ();
+				var initialBody = body.Instructions.ToList ();
+				var head = initialBody.First ();
+				var opcode = worker.Create (OpCodes.Ldc_I4_1);
+				worker.InsertBefore (head, opcode);
+				worker.InsertBefore (head, worker.Create (OpCodes.Ret));
+				initialBody.ForEach (worker.Remove);
+				AssertOpCodeSequence (new [] { OpCodes.Ldc_I4_1, OpCodes.Ret }, pathGetterDef.body);	
+			}
+		}
+
+		[Test]
 		public void InsertAfter ()
 		{
 			var method = CreateTestMethod (OpCodes.Ldloc_0, OpCodes.Ldloc_2, OpCodes.Ldloc_3);
diff --git a/Test/Resources/assemblies/Issue697.dll b/Test/Resources/assemblies/Issue697.dll
new file mode 100644
index 0000000..6310d6c
--- /dev/null
+++ b/Test/Resources/assemblies/Issue697.dll
diff --git a/Test/Resources/assemblies/Issue697.dll.mdb b/Test/Resources/assemblies/Issue697.dll.mdb
new file mode 100644
index 0000000..862bd59
--- /dev/null
+++ b/Test/Resources/assemblies/Issue697.dll.mdb