allow the user to supply multiple passwords for decryption

previously the only way to test if a password was correct was to supply a single password and throw if the value was incorrect. this was slow. now parsing options supports a list of passwords as well as a single password option (which is equivalent to a list with a single item). these passwords are all tested at the same time and an exception is only thrown once all passwords are tested.

src/UglyToad.PdfPig.Tests/Integration/EncryptedDocumentTests.cs

@@ -0,0 +1,53 @@
+namespace UglyToad.PdfPig.Tests.Integration
+{
+    using System;
+    using System.Collections.Generic;
+    using Exceptions;
+    using Xunit;
+
+    public class EncryptedDocumentTests
+    {
+        private const string FileName = "encrypted-password-is-password.pdf";
+        private const string Password = "password";
+
+        [Fact]
+        public void NoPasswordThrows()
+        {
+            Action action = () => PdfDocument.Open(GetPath());
+
+            Assert.Throws<PdfDocumentEncryptedException>(action);
+        }
+
+        [Fact]
+        public void CanOpenDocumentAndGetPage()
+        {
+            using (var document = PdfDocument.Open(GetPath(), new ParsingOptions
+            {
+                Password = Password
+            }))
+            {
+                foreach (var page in document.GetPages())
+                {
+                    Assert.NotNull(page.Text);
+                }
+            }
+        }
+
+        [Fact]
+        public void CanProvideMultiplePasswords()
+        {
+            using (var document = PdfDocument.Open(GetPath(), new ParsingOptions
+            {
+                Passwords = new List<string> { "pangolin", "harpsichord", Password }
+            }))
+            {
+                foreach (var page in document.GetPages())
+                {
+                    Assert.NotNull(page.Text);
+                }
+            }
+        }
+
+        private static string GetPath() => IntegrationHelpers.GetSpecificTestDocumentPath(FileName);
+    }
+}

src/UglyToad.PdfPig.Tests/UglyToad.PdfPig.Tests.csproj

@@ -29,6 +29,9 @@
     <Content Include="Integration\Documents\*">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Integration\SpecificTestDocuments\*">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
   </ItemGroup>
 
   <ItemGroup>
@@ -73,8 +76,6 @@
     <Content Include="Fonts\Type1\CMBX12.pfa" />
     <Content Include="Fonts\Type1\CMCSC10.pfa" />
     <Content Include="Fonts\Type1\Raleway-Black.pfb" />
-    <Content Include="Integration\SpecificTestDocuments\invalid-xref-loop.pdf" />
-    <Content Include="Integration\SpecificTestDocuments\custom-properties.pdf" />
     <Content Include="Parser\SimpleGoogleDocPageContent.txt">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>