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[http-client-csharp] Add preserveUnderscores option to ToIdentifierName and ToVariableName #10062

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Merged
JoshLove-msft merged 2 commits into from
Mar 17, 2026
Merged

[http-client-csharp] Add preserveUnderscores option to ToIdentifierName and ToVariableName #10062

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9b8a262
Initial plan
Copilot Mar 17, 2026
ff3ae16
feat: add preserveUnderscores parameter to ToIdentifierName and ToVar…
Copilot Mar 17, 2026
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11 changes: 6 additions & 5 deletions ...nt-csharp/generator/Microsoft.TypeSpec.Generator.Input/src/Extensions/StringExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,11 @@ namespace Microsoft.TypeSpec.Generator.Input.Extensions
{
public static class StringExtensions
{
private static bool IsWordSeparator(char c) => !SyntaxFacts.IsIdentifierPartCharacter(c) || c == '_';
private static bool IsWordSeparator(char c, bool preserveUnderscores = false)
=> !SyntaxFacts.IsIdentifierPartCharacter(c) || (!preserveUnderscores && c == '_');

[return: NotNullIfNotNull("name")]
public static string ToIdentifierName(this string name, bool useCamelCase = false)
public static string ToIdentifierName(this string name, bool useCamelCase = false, bool preserveUnderscores = false)
{
if (string.IsNullOrEmpty(name))
{
Expand All @@ -39,7 +40,7 @@ public static string ToIdentifierName(this string name, bool useCamelCase = fals
for (; i < name.Length; i++)
{
var c = name[i];
if (IsWordSeparator(c))
if (IsWordSeparator(c, preserveUnderscores))
{
upperCase = true;
continue;
Expand All @@ -56,7 +57,7 @@ public static string ToIdentifierName(this string name, bool useCamelCase = fals
upperCase = false;
// grow the first word length when this letter follows by two other upper case letters
// this happens in OSProfile, where OS is the first word
if (i + 2 < name.Length && char.IsUpper(name[i + 1]) && (char.IsUpper(name[i + 2]) || IsWordSeparator(name[i + 2])))
if (i + 2 < name.Length && char.IsUpper(name[i + 1]) && (char.IsUpper(name[i + 2]) || IsWordSeparator(name[i + 2], preserveUnderscores)))
firstWordLength++;
// grow the first word length when this letter follows by another upper case letter and an end of the string
// this happens when the string only has one word, like OS, DNS
Expand All @@ -77,6 +78,6 @@ public static string ToIdentifierName(this string name, bool useCamelCase = fals
}

[return: NotNullIfNotNull(nameof(name))]
public static string ToVariableName(this string name) => name.ToIdentifierName(useCamelCase: true);
public static string ToVariableName(this string name, bool preserveUnderscores = false) => name.ToIdentifierName(useCamelCase: true, preserveUnderscores: preserveUnderscores);
}
}
51 changes: 51 additions & 0 deletions ...-client-csharp/generator/Microsoft.TypeSpec.Generator.Input/test/StringExtensionsTests.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,51 @@
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

using Microsoft.TypeSpec.Generator.Input.Extensions;
using NUnit.Framework;

namespace Microsoft.TypeSpec.Generator.Input.Tests
{
public class StringExtensionsTests
{
// Existing behavior without preserveUnderscores (default)
[TestCase("Tls_1_0", false, "Tls10")]
[TestCase("hello_world", false, "HelloWorld")]
[TestCase("_leading", false, "Leading")]
[TestCase("trailing_", false, "Trailing")]
[TestCase("UPPER_CASE", false, "UPPERCASE")]
[TestCase("simple", false, "Simple")]
[TestCase("", false, "")]
[TestCase(null, false, null)]
// New behavior with preserveUnderscores = true
[TestCase("Tls_1_0", true, "Tls_1_0")]
[TestCase("hello_world", true, "Hello_world")]
[TestCase("_leading", true, "_leading")]
[TestCase("trailing_", true, "Trailing_")]
[TestCase("UPPER_CASE", true, "UPPER_CASE")]
[TestCase("simple", true, "Simple")]
[TestCase("", true, "")]
[TestCase(null, true, null)]
[TestCase("TLS_1_0", true, "TLS_1_0")]
[TestCase("foo__bar", true, "Foo__bar")]
public void TestToIdentifierNamePreserveUnderscores(string name, bool preserveUnderscores, string expected)
{
var result = name.ToIdentifierName(preserveUnderscores: preserveUnderscores);
Assert.AreEqual(expected, result);
}

// Existing behavior of ToVariableName without preserveUnderscores
[TestCase("HelloWorld", false, "helloWorld")]
[TestCase("Tls_1_0", false, "tls10")]
[TestCase("UPPER_CASE", false, "upperCASE")]
// New behavior with preserveUnderscores = true
[TestCase("HelloWorld", true, "helloWorld")]
[TestCase("Tls_1_0", true, "tls_1_0")]
[TestCase("UPPER_CASE", true, "uppeR_CASE")]
public void TestToVariableNamePreserveUnderscores(string name, bool preserveUnderscores, string expected)
{
var result = name.ToVariableName(preserveUnderscores: preserveUnderscores);
Assert.AreEqual(expected, result);
}
}
}
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