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Refactor ChangedText.Merge and add fuzz testing (#48420)
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@RikkiGibson
RikkiGibson authored Oct 12, 2020
1 parent 346de17 commit ed1ed1d
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Showing 4 changed files with 647 additions and 148 deletions.
334 changes: 331 additions & 3 deletions src/Compilers/Core/CodeAnalysisTest/Text/TextChangeTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,18 +5,27 @@
#nullable disable

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Text;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Test.Utilities;
using Xunit;
using System.Collections.Generic;
using Xunit.Abstractions;

namespace Microsoft.CodeAnalysis.UnitTests
{
public class TextChangeTests
{
private readonly ITestOutputHelper _output;

public TextChangeTests(ITestOutputHelper output)
{
_output = output;
}

[Fact]
public void TestSubTextStart()
{
Expand Down Expand Up @@ -803,6 +812,19 @@ public void TestMergeChanges_SameStart_AndBothHaveDeletion_NewDeletionSmallerTha
Assert.Equal(new[] { new TextChange(new TextSpan(1, 3), "bba") }, changes);
}

[Fact]
[WorkItem(39405, "https://github.com/dotnet/roslyn/issues/39405")]
public void TestMergeChanges_NewDeletionLargerThanOld()
{
var original = SourceText.From("01234");
var change1 = original.WithChanges(new TextChange(new TextSpan(1, 3), "aa"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(1, 3), "bb"));

var changes = change2.GetTextChanges(original);
Assert.Equal("0aa4", change1.ToString());
Assert.Equal("0bb", change2.ToString());
}

[Fact]
public void TestMergeChanges_AfterAdjacent()
{
Expand Down Expand Up @@ -904,12 +926,318 @@ public void TestMergeChanges_IntegrationTestCase1()
new TextChangeRange(new TextSpan(919, 10), 468),
new TextChangeRange(new TextSpan(936, 33), 33),
new TextChangeRange(new TextSpan(1098, 0), 70),
new TextChangeRange(new TextSpan(1125, 4), 34),
new TextChangeRange(new TextSpan(1134, 0), 4),
new TextChangeRange(new TextSpan(1125, 4), 38),
new TextChangeRange(new TextSpan(1138, 0), 47));
Assert.Equal<TextChangeRange>(expected, merged);
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void DebuggerDisplay()
{
Assert.Equal("new TextChange(new TextSpan(0, 0), null)", default(TextChange).GetDebuggerDisplay());
Assert.Equal("new TextChange(new TextSpan(0, 1), \"abc\")", new TextChange(new TextSpan(0, 1), "abc").GetDebuggerDisplay());
Assert.Equal("new TextChange(new TextSpan(0, 1), (NewLength = 10))", new TextChange(new TextSpan(0, 1), "0123456789").GetDebuggerDisplay());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz()
{
var random = new Random();

// Adjust upper bound as needed to generate a simpler reproducer for an error scenario
var originalText = SourceText.From(string.Join("", Enumerable.Range(0, random.Next(10))));

for (var iteration = 0; iteration < 100000; iteration++)
{
var editedLength = originalText.Length;
ArrayBuilder<TextChange> oldChangesBuilder = ArrayBuilder<TextChange>.GetInstance();

// Adjust as needed to get a simpler error reproducer.
var oldMaxInsertLength = originalText.Length * 2;
const int maxSkipLength = 2;
// generate sequence of "old edits" which meet invariants
for (int i = 0; i < originalText.Length; i += random.Next(maxSkipLength))
{
var newText = string.Join("", Enumerable.Repeat('a', random.Next(oldMaxInsertLength)));
var newChange = new TextChange(new TextSpan(i, length: random.Next(originalText.Length - i)), newText);
i = newChange.Span.End;

editedLength = editedLength - newChange.Span.Length + newChange.NewText.Length;
oldChangesBuilder.Add(newChange);

// Adjust as needed to generate a simpler reproducer for an error scenario
if (oldChangesBuilder.Count == 5) break;
}

var change1 = originalText.WithChanges(oldChangesBuilder);

ArrayBuilder<TextChange> newChangesBuilder = ArrayBuilder<TextChange>.GetInstance();

// Adjust as needed to get a simpler error reproducer.
var newMaxInsertLength = editedLength * 2;
// generate sequence of "new edits" which meet invariants
for (int i = 0; i < editedLength; i += random.Next(maxSkipLength))
{
var newText = string.Join("", Enumerable.Repeat('b', random.Next(newMaxInsertLength)));
var newChange = new TextChange(new TextSpan(i, length: random.Next(editedLength - i)), newText);
i = newChange.Span.End;

newChangesBuilder.Add(newChange);

// Adjust as needed to generate a simpler reproducer for an error scenario
if (newChangesBuilder.Count == 5) break;
}

var change2 = change1.WithChanges(newChangesBuilder);
try
{
var textChanges = change2.GetTextChanges(originalText);
Assert.Equal(originalText.WithChanges(textChanges).ToString(), change2.ToString());
}
catch
{
_output.WriteLine($@"
[Fact]
public void Fuzz_{iteration}()
{{
var originalText = SourceText.From(""{originalText}"");
var change1 = originalText.WithChanges({string.Join(", ", oldChangesBuilder.Select(c => c.GetDebuggerDisplay()))});
var change2 = change1.WithChanges({string.Join(", ", newChangesBuilder.Select(c => c.GetDebuggerDisplay()))});
Assert.Equal(""{change1}"", change1.ToString()); // double-check for correctness
Assert.Equal(""{change2}"", change2.ToString()); // double-check for correctness
var changes = change2.GetTextChanges(originalText);
Assert.Equal(""{change2}"", originalText.WithChanges(changes).ToString());
}}
");
throw;
}
finally
{
// we delay freeing so that if we need to debug the fuzzer
// it's easier to see what changes were introduced at each stage.
oldChangesBuilder.Free();
newChangesBuilder.Free();
}
}
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_0()
{
var originalText = SourceText.From("01234");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 2), "a"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 2), "bb"));
Assert.Equal("a234", change1.ToString());
Assert.Equal("bb34", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("bb34", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_1()
{
var original = SourceText.From("01234");
var change1 = original.WithChanges(new TextChange(new TextSpan(0, 0), "aa"), new TextChange(new TextSpan(1, 1), "aa"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 1), "b"), new TextChange(new TextSpan(2, 2), ""));

var changes = change2.GetTextChanges(original);
Assert.Equal("aa0aa234", change1.ToString());
Assert.Equal("baa234", change2.ToString());
Assert.Equal(change2.ToString(), original.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_2()
{
var originalText = SourceText.From("01234");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 0), "a"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 2), ""), new TextChange(new TextSpan(2, 0), "bb"));
Assert.Equal("a01234", change1.ToString());
Assert.Equal("bb1234", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("bb1234", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_3()
{
var originalText = SourceText.From("01234");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 1), "aa"), new TextChange(new TextSpan(3, 1), "aa"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 0), "bbb"));
Assert.Equal("aa12aa4", change1.ToString());
Assert.Equal("bbbaa12aa4", change2.ToString());
var changes = change2.GetTextChanges(originalText);
Assert.Equal("bbbaa12aa4", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_4()
{
var originalText = SourceText.From("012345");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 3), "a"), new TextChange(new TextSpan(5, 0), "aaa"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 2), ""), new TextChange(new TextSpan(3, 1), "bb"));
Assert.Equal("a34aaa5", change1.ToString());
Assert.Equal("4bbaa5", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("4bbaa5", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_7()
{
var originalText = SourceText.From("01234567");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 1), "aaaaa"), new TextChange(new TextSpan(3, 1), "aaaa"), new TextChange(new TextSpan(6, 1), "aaaaa"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 0), "b"), new TextChange(new TextSpan(2, 0), "b"), new TextChange(new TextSpan(3, 4), "bbbbb"), new TextChange(new TextSpan(9, 5), "bbbbb"), new TextChange(new TextSpan(15, 3), ""));
Assert.Equal("aaaaa12aaaa45aaaaa7", change1.ToString());
Assert.Equal("baababbbbbaabbbbba7", change2.ToString());


var changes = change2.GetTextChanges(originalText);
Assert.Equal("baababbbbbaabbbbba7", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_10()
{
var originalText = SourceText.From("01234");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 1), "a"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 1), "b"), new TextChange(new TextSpan(2, 2), "b"));
Assert.Equal("a1234", change1.ToString());
Assert.Equal("b1b4", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("b1b4", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_23()
{
var originalText = SourceText.From("01234");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 1), "aa"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 0), "b"), new TextChange(new TextSpan(1, 2), "b"));
Assert.Equal("aa1234", change1.ToString());
Assert.Equal("bab234", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("bab234", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_32()
{
var originalText = SourceText.From("012345");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 2), "a"), new TextChange(new TextSpan(3, 2), "a"));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 3), "bbb"));
Assert.Equal("a2a5", change1.ToString());
Assert.Equal("bbb5", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("bbb5", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_39()
{
var originalText = SourceText.From("0123456");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 4), ""), new TextChange(new TextSpan(5, 1), ""));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 1), ""), new TextChange(new TextSpan(1, 0), ""));
Assert.Equal("46", change1.ToString());
Assert.Equal("6", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("6", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_55()
{
var originalText = SourceText.From("012345");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 2), ""), new TextChange(new TextSpan(3, 1), ""), new TextChange(new TextSpan(4, 0), ""), new TextChange(new TextSpan(4, 0), ""), new TextChange(new TextSpan(4, 0), ""));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 1), ""), new TextChange(new TextSpan(1, 1), ""), new TextChange(new TextSpan(2, 0), ""));
Assert.Equal("245", change1.ToString());
Assert.Equal("5", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("5", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(47234, "https://github.com/dotnet/roslyn/issues/47234")]
public void Fuzz_110()
{
var originalText = SourceText.From("01234");
var change1 = originalText.WithChanges(new TextChange(new TextSpan(0, 1), ""), new TextChange(new TextSpan(2, 1), ""));
var change2 = change1.WithChanges(new TextChange(new TextSpan(0, 0), ""), new TextChange(new TextSpan(1, 1), ""));
Assert.Equal("134", change1.ToString());
Assert.Equal("14", change2.ToString());

var changes = change2.GetTextChanges(originalText);
Assert.Equal("14", originalText.WithChanges(changes).ToString());
}

[Fact]
[WorkItem(41413, "https://github.com/dotnet/roslyn/issues/41413")]
public void GetTextChanges_NonOverlappingSpans()
{
var content = @"@functions{
public class Foo
{
void Method()
{
}
}
}";

var text = SourceText.From(content);
var edits1 = new TextChange[]
{
new TextChange(new TextSpan(39, 0), " "),
new TextChange(new TextSpan(42, 0), " "),
new TextChange(new TextSpan(57, 0), " "),
new TextChange(new TextSpan(58, 0), "\r\n"),
new TextChange(new TextSpan(64, 2), " "),
new TextChange(new TextSpan(69, 0), " "),
};
var changedText = text.WithChanges(edits1);

var edits2 = new TextChange[]
{
new TextChange(new TextSpan(35, 4), string.Empty),
new TextChange(new TextSpan(46, 4), string.Empty),
new TextChange(new TextSpan(73, 4), string.Empty),
new TextChange(new TextSpan(88, 0), " "),
new TextChange(new TextSpan(90, 4), string.Empty),
new TextChange(new TextSpan(105, 4), string.Empty),
};
var changedText2 = changedText.WithChanges(edits2);

var changes = changedText2.GetTextChanges(text);

var position = 0;
foreach (var change in changes)
{
Assert.True(position <= change.Span.Start);
position = change.Span.End;
}
}
private SourceText GetChangesWithoutMiddle(
SourceText original,
Func<SourceText, SourceText> fnChange1,
Expand Down
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