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Merged
SimonCropp merged 2 commits into from
Aug 14, 2026
Merged

Single line literal #759

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439c494
Render a single line snapshot as a regular literal
SimonCropp Aug 14, 2026
b213fb5
Keep a regular literal on the call line
SimonCropp Aug 14, 2026
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50 changes: 49 additions & 1 deletion src/DiffEngine.Tests/CsStringLiteralTests.cs
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Open in desktop
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
public class CsStringLiteralTests
public class CsStringLiteralTests
{
static readonly string[] renderRoundTripCases =
[
Expand Down Expand Up @@ -105,6 +105,54 @@ public async Task RenderRoundTrips()
}
}

// A single line snapshot says nothing a raw string can say, and costs three lines to say it
[Test]
[Arguments("abc", "\"abc\"")]
[Arguments("", "\"\"")]
[Arguments(" ", "\" \"")]
[Arguments("has \"quotes\"", "\"has \\\"quotes\\\"\"")]
[Arguments("back\\slash", "\"back\\\\slash\"")]
[Arguments("tab\there", "\"tab\\there\"")]
[Arguments("bell\a", "\"bell\\a\"")]
[Arguments("esc\u001b", "\"esc\\u001b\"")]
[Arguments("emoji 🎈 and unicode ☂", "\"emoji 🎈 and unicode ☂\"")]
[Arguments("$ {value} {{x}}", "\"$ {value} {{x}}\"")]
public async Task RenderSingleLineIsRegular(string content, string expected)
{
var rendered = CsStringLiteral.Render(content, " ", "\n");
await Assert.That(rendered).IsEqualTo(expected);
}

[Test]
[Arguments("a\nb")]
[Arguments("a\rb")]
[Arguments("a\r\nb")]
[Arguments("\nabc")]
[Arguments("abc\n")]
public async Task RenderMultiLineIsRaw(string content)
{
var rendered = CsStringLiteral.Render(content, " ", "\n");
await Assert.That(rendered).IsEqualTo(CsStringLiteral.RenderRaw(content, " ", "\n"));
}

[Test]
public async Task RenderRoundTripsWhicheverFormItPicks()
{
foreach (var content in renderRoundTripCases)
{
foreach (var eol in new[] { "\n", "\r\n" })
{
foreach (var indent in new[] { "", " ", "\t\t" })
{
var rendered = CsStringLiteral.Render(content, indent, eol);
var parsed = CsStringLiteral.TryParse(rendered, out var value);
await Assert.That(parsed).IsTrue();
await Assert.That(value).IsEqualTo(content);
}
}
}
}

[Test]
[Arguments("\"a\"", "a")]
[Arguments("\"\"", "")]
Expand Down
83 changes: 43 additions & 40 deletions src/DiffEngine.Tests/InlinePatcherTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,7 @@ public async Task ReplaceRegularLiteral()
var source = Method(" await Snapshot(\"old\");");
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, "\"old\"", "new", out var newSource, out _);
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" await Snapshot(\n" +
" \"\"\"\n" +
" new\n" +
" \"\"\");");
await Assert.That(newSource).Contains(" await Snapshot(\"new\");");
}

[Test]
Expand Down Expand Up @@ -225,7 +221,7 @@ public async Task InsertIntoEmptyArgumentList()
var source = Method(" await Snapshot();");
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "new", out var newSource, out _);
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await Snapshot(\n \"\"\"\n new\n \"\"\");");
await Assert.That(newSource).Contains("await Snapshot(\"new\");");
}

[Test]
Expand All @@ -234,7 +230,7 @@ public async Task InsertReplacesNullArgument()
var source = Method(" await Snapshot(null, file, line);");
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "new", out var newSource, out _);
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await Snapshot(\n \"\"\"\n new\n \"\"\", file, line);");
await Assert.That(newSource).Contains("await Snapshot(\"new\", file, line);");
}

[Test]
Expand All @@ -243,7 +239,7 @@ public async Task InsertBeforeAnotherNamedArgument()
var source = Method(" await Snapshot(file: myFile);");
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "new", out var newSource, out _);
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await Snapshot(expected: \"\"\"\n new\n \"\"\", file: myFile);");
await Assert.That(newSource).Contains("await Snapshot(expected: \"new\", file: myFile);");
}

[Test]
Expand Down Expand Up @@ -287,12 +283,27 @@ public async Task AppendToABareVerify()

var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" await Verify(value)\n" +
" .Snapshot(\"new\");");
}

// The raw form is the one that has to sit on its own line, indented under the call
[Test]
public async Task AppendMultiLineContent()
{
var source = Method(" await Verify(value);");

var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "a\nb", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" await Verify(value)\n" +
" .Snapshot(\n" +
" \"\"\"\n" +
" new\n" +
" a\n" +
" b\n" +
" \"\"\");");
}

Expand All @@ -310,10 +321,7 @@ public async Task AppendGoesAfterAnExistingChain()
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" .ScrubLinesContaining(\"x\")\n" +
" .Snapshot(\n" +
" \"\"\"\n" +
" new\n" +
" \"\"\");");
" .Snapshot(\"new\");");
}

[Test]
Expand All @@ -324,7 +332,7 @@ public async Task AppendToAnEntryPointOverload()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await VerifyXml(value)\n .Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("await VerifyXml(value)\n .Snapshot(\"new\");");
}

// The verify call spans lines, so the closing paren is nowhere near the hint
Expand All @@ -341,7 +349,7 @@ public async Task AppendToAMultiLineVerifyCall()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(" })\n .Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains(" })\n .Snapshot(\"new\");");
}

[Test]
Expand Down Expand Up @@ -411,8 +419,7 @@ public async Task AppendPrefersTheEntryPointOverANestedHelper()
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" await Verify(ContentValidation.Verify(value))\n" +
" .Snapshot(\n" +
" \"\"\"");
" .Snapshot(\"new\");");
}

[Test]
Expand All @@ -423,7 +430,7 @@ public async Task AppendToAVerifierQualifiedCall()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await Verifier.Verify(value)\n .Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("await Verifier.Verify(value)\n .Snapshot(\"new\");");
}

[Test]
Expand All @@ -434,7 +441,7 @@ public async Task AppendToAThisQualifiedCall()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await this.Verify(value)\n .Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("await this.Verify(value)\n .Snapshot(\"new\");");
}

[Test]
Expand Down Expand Up @@ -530,9 +537,9 @@ public async Task RemoveWithNoSnapshotCall()
public async Task TabIndentedFileUsesTabUnit()
{
var source = "class Tests\n{\n\tasync Task Test()\n\t{\n\t\tawait Snapshot();\n\t}\n}";
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "new", out var newSource, out _);
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "a\nb", out var newSource, out _);
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("Snapshot(\n\t\t\t\"\"\"\n\t\t\tnew\n\t\t\t\"\"\");");
await Assert.That(newSource).Contains("Snapshot(\n\t\t\t\"\"\"\n\t\t\ta\n\t\t\tb\n\t\t\t\"\"\");");
}

[Test]
Expand All @@ -541,8 +548,7 @@ public async Task HintBeyondEndOfFile()
var source = "await Snapshot();";
var status = InlinePatcher.TryApply(source, 500, InlinePatchMode.Set, null, "new", out var newSource, out _);
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
// No newline in the file, so the splice falls back to the environment's
await Assert.That(newSource).Contains($"Snapshot({Environment.NewLine} \"\"\"");
await Assert.That(newSource).Contains("Snapshot(\"new\");");
}

[Test]
Expand Down Expand Up @@ -696,14 +702,14 @@ public async Task MixedEolFileLeavesUntouchedRegionsAlone()
var suffix = "\r\n// trailing\n// mixed tail\n";
var source = prefix + body + suffix;

var status = InlinePatcher.TryApply(source, 7, InlinePatchMode.Set, "\"old\"", "new", out var newSource, out _);
var status = InlinePatcher.TryApply(source, 7, InlinePatchMode.Set, "\"old\"", "new1\nnew2", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
// Untouched regions keep their original endings byte for byte
await Assert.That(newSource.StartsWith(prefix, StringComparison.Ordinal)).IsTrue();
await Assert.That(newSource.EndsWith(suffix, StringComparison.Ordinal)).IsTrue();
// The spliced literal uses the file's dominant ending
await Assert.That(newSource).Contains("\"\"\"\r\n new\r\n \"\"\"");
await Assert.That(newSource).Contains("Snapshot(\r\n \"\"\"\r\n new1\r\n new2\r\n \"\"\");");
}

[Test]
Expand All @@ -725,8 +731,7 @@ public async Task SameLiteralInTheVerifyArgumentIsNotPatched()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, "\"same\"", "changed", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await Verify(\"same\").Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("changed");
await Assert.That(newSource).Contains("await Verify(\"same\").Snapshot(\"changed\");");
}

// The expression search must match a whole argument, not the quoted part of a longer literal
Expand Down Expand Up @@ -768,7 +773,7 @@ public async Task CommentedOutCallIsSkipped()

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(" // await Verify(x).Snapshot(\"doc example\");\n");
await Assert.That(newSource).Contains(" await Verify(x).Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains(" await Verify(x).Snapshot(\"new\");");
}

[Test]
Expand All @@ -782,7 +787,7 @@ public async Task CallInsideAStringIsSkipped()

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("var text = \"await Snapshot(\\\"x\\\")\";\n");
await Assert.That(newSource).Contains("await Verify(x).Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("await Verify(x).Snapshot(\"new\");");
}

// A declaration is a name followed by parens too, so it has to be told apart by what precedes it
Expand Down Expand Up @@ -818,8 +823,7 @@ public async Task AppendSkipsAVerifyPrefixedDeclaration()
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" Task VerifyThing(string value) => Verify(value)\n" +
" .Snapshot(\n" +
" \"\"\"");
" .Snapshot(\"new\");");
}

// Snapshot terminates the chain, so a comment in the middle of one must not end the walk
Expand All @@ -835,8 +839,7 @@ public async Task AppendGoesAfterACommentInTheChain()
await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(
" .UseDirectory(\"snapshots\")\n" +
" .Snapshot(\n" +
" \"\"\"");
" .Snapshot(\"new\");");
}

[Test]
Expand All @@ -850,7 +853,7 @@ public async Task LiteralInACommentIsNotPatched()

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("// was \"old\"\n");
await Assert.That(newSource).Contains("Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("Snapshot(\"new\");");
}

[Test]
Expand All @@ -870,7 +873,7 @@ public async Task LiteralInAnotherMethodIsNotPatched()

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("void Helper() => Log(\"old\");");
await Assert.That(newSource).Contains("Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("Snapshot(\"new\");");
}

// The empty literal is two characters, and the opening of every raw literal holds a pair
Expand All @@ -894,7 +897,7 @@ public async Task EmptyOriginalIsNotMatchedInsideARawDelimiter()

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(" content\n \"\"\");");
await Assert.That(newSource).Contains("Verify(b).Snapshot(\n \"\"\"\n new\n \"\"\");");
await Assert.That(newSource).Contains("Verify(b).Snapshot(\"new\");");
}

[Test]
Expand All @@ -905,7 +908,7 @@ public async Task GenericSnapshotCall()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains(".Snapshot<Thing>(\n \"\"\"");
await Assert.That(newSource).Contains(".Snapshot<Thing>(\"new\");");
}

[Test]
Expand All @@ -916,7 +919,7 @@ public async Task AppendToAGenericVerify()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Append, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("await Verify<Thing>(value)\n .Snapshot(\n \"\"\"");
await Assert.That(newSource).Contains("await Verify<Thing>(value)\n .Snapshot(\"new\");");
}

[Test]
Expand All @@ -927,7 +930,7 @@ public async Task CommentInTheArgumentListIsNotTheArgument()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, null, "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("Snapshot(/* keep */\n \"\"\"");
await Assert.That(newSource).Contains("Snapshot(/* keep */\"new\");");
}

[Test]
Expand All @@ -938,7 +941,7 @@ public async Task CommentAfterTheArgumentIsKept()
var status = InlinePatcher.TryApply(source, 5, InlinePatchMode.Set, "\"old\"", "new", out var newSource, out _);

await Assert.That(status).IsEqualTo(PatchStatus.Applied);
await Assert.That(newSource).Contains("\"\"\" /* why */);");
await Assert.That(newSource).Contains("\"new\" /* why */);");
}

// Pulling the call up onto the line above would take the semicolon into the comment
Expand Down
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