feature: add max file size finder

Tests/EncryptionTests/FileEncryptionTest.cs

@@ -31,28 +31,16 @@ public class FileEncryptionTest {
         _encryptedFile = _encryption.Encrypt(_sourceFile);
     }
 
-    [Ignore("Test takes too long")]
-    [TestCase(1)]
+    [Ignore("Takes much to long")]
     [TestCase(500)]
     [TestCase(600)]
     [TestCase(700)]
+    [TestCase(750)]
     [TestCase(800)]
     [TestCase(1000)]
     [TestCase(2000)]
     [TestCase(2047)]
     public void EncryptLargeFiles_ShouldPass(int fileSizeInMb) {
-        Console.WriteLine($"Encrypting {int.MaxValue / (1024*1024)} MB file");
-        var randomdMb = "";
-        for (int i = 0 ; i < (1024*1024 - 1) ; i++) {
-            randomdMb += "a";
-        }
-
-        var maxString = "";
-        for (int i = 0; i < int.MaxValue / (1024*1024); i++) {
-            maxString += randomdMb;
-        }
-
-        Console.WriteLine($"Max String is {maxString.Length  / (1024*1024)} MB long");
         // Arrange
         var sourceFile = RandomNumberGenerator.GetBytes(1024 * 1024 * fileSizeInMb);
         Console.WriteLine($"Encrypting {fileSizeInMb} MB file");
@@ -65,7 +53,24 @@ public class FileEncryptionTest {
 
         // Assert
         encryptedFile.Should().NotBeNullOrEmpty();
+    }
 
+    [Ignore("Takes much to long")]
+    [Test]
+    public void FindMaxFileSizeForEncryption() {
+        for (var start = 750; start < 800; start++) {
+            Console.Write($"Trying to encrypt {start} MB file");
+            try {
+                EncryptLargeFiles_ShouldPass(start);
+                Console.WriteLine("...success");
+            }
+            catch (Exception e) {
+                Console.WriteLine("...failed");
+                Console.WriteLine(e);
+                Console.WriteLine($"Max file size for encryption is {start - 1} MB");
+                break;
+            }
+        }
     }
 
     [Test]
@@ -102,7 +107,9 @@ public class FileEncryptionTest {
 }";
 
         Assert.Throws<EncryptionException>(() => {
-            var result = new FitEncryption(new List<string> { "" }, "", null)
+            var result = new FitEncryption(new List<string> {
+                    ""
+                }, "", null)
                 .Encrypt("Test", jsonWebKeyString);
             Console.WriteLine(result);
         });