Add check to allow underscores in test functions marked with @test attribute

Author: hamtiko

Documentation/RuleDocumentation.md

@@ -79,6 +79,7 @@ Underscores (except at the beginning of an identifier) are disallowed.
 
 This rule does not apply to test code, defined as code which:
   * Contains the line `import XCTest`
+  * The function is marked with `@Test` attribute
 
 Lint: If an identifier contains underscores or begins with a capital letter, a lint error is
       raised.

Sources/SwiftFormat/Rules/AlwaysUseLowerCamelCase.swift

@@ -100,7 +100,11 @@ public final class AlwaysUseLowerCamelCase: SyntaxLintRule {
 
     // We allow underscores in test names, because there's an existing convention of using
     // underscores to separate phrases in very detailed test names.
-    let allowUnderscores = testCaseFuncs.contains(node)
+    let allowUnderscores = testCaseFuncs.contains(node) || node.attributes.contains {
+      // Allow underscore for test functions with the `@Test` attribute.
+      $0.as(AttributeSyntax.self)?.attributeName.as(IdentifierTypeSyntax.self)?.name.text == "Test"
+    }
+
     diagnoseLowerCamelCaseViolations(
       node.name, allowUnderscores: allowUnderscores,
       description: identifierDescription(for: node))

Tests/SwiftFormatTests/Rules/AlwaysUseLowerCamelCaseTests.swift

@@ -210,4 +210,24 @@ final class AlwaysUseLowerCamelCaseTests: LintOrFormatRuleTestCase {
       ]
     )
   }
+
+  func testIgnoresFunctionsWithTestAttributes() {
+    assertLint(
+      AlwaysUseLowerCamelCase.self,
+      """
+      @Test
+      func function_With_Test_Attribute() {}
+      @Test("Description for test functions",
+            .tags(.testTag))
+      func function_With_Test_Attribute_And_Args() {}
+      func 1️⃣function_Without_Test_Attribute() {}
+      @objc
+      func 2️⃣function_With_Non_Test_Attribute() {}
+      """,
+      findings: [
+        FindingSpec("1️⃣", message: "rename the function 'function_Without_Test_Attribute' using lowerCamelCase"),
+        FindingSpec("2️⃣", message: "rename the function 'function_With_Non_Test_Attribute' using lowerCamelCase"),
+      ]
+    )
+  }
 }