Ensure that content is complete using a queue

Source/SwiftLintCore/Models/Issue.swift

@@ -84,7 +84,7 @@ public enum Issue: LocalizedError, Equatable {
     /// Flag to enable warnings for deprecations being printed to the console. Printing is enabled by default.
     package nonisolated(unsafe) static var printDeprecationWarnings = true
 
-    @TaskLocal private static var messageConsumer: (@Sendable (String) -> Void)?
+    @TaskLocal private static var printQueueContinuation: AsyncStream<String>.Continuation?
 
     /// Hook used to capture all messages normally printed to stdout and return them back to the caller.
     ///
@@ -95,18 +95,10 @@ public enum Issue: LocalizedError, Equatable {
     /// - returns: The collected messages produced while running the code in the runner.
     @MainActor
     static func captureConsole(runner: @Sendable () throws -> Void) async rethrows -> String {
-        actor Console {
-            static var content = ""
-        }
-        defer {
-            Console.content = ""
-        }
-        try $messageConsumer.withValue(
-            { Console.content += (Console.content.isEmpty ? "" : "\n") + $0 },
-            operation: runner
-        )
-        await Task.yield()
-        return Console.content
+        let (stream, continuation) = AsyncStream.makeStream(of: String.self)
+        try $printQueueContinuation.withValue(continuation, operation: runner)
+        continuation.finish()
+        return await stream.reduce(into: "") { @Sendable in $0 += $0.isEmpty ? $1 : "\n\($1)" }
     }
 
     /// Wraps any `Error` into a `SwiftLintError.genericWarning` if it is not already a `SwiftLintError`.
@@ -140,13 +132,8 @@ public enum Issue: LocalizedError, Equatable {
         if case .ruleDeprecated = self, !Self.printDeprecationWarnings {
             return
         }
-        Task(priority: .high) { @MainActor in
-            if let consumer = Self.messageConsumer {
-                consumer(errorDescription)
-            } else {
-                queuedPrintError(errorDescription)
-            }
-        }
+        Self.printQueueContinuation?.yield(errorDescription)
+        queuedPrintError(errorDescription)
     }
 
     private var message: String {

Tests/BuiltInRulesTests/ExplicitTypeInterfaceConfigurationTests.swift

@@ -25,11 +25,12 @@ final class ExplicitTypeInterfaceConfigurationTests: SwiftLintTestCase {
     }
 
     func testInvalidKeyInCustomConfiguration() async throws {
-        try await AsyncAssertEqual(
-            try await Issue.captureConsole {
-                var config = ExplicitTypeInterfaceConfiguration()
-                try config.apply(configuration: ["invalidKey": "error"])
-            },
+        let console = try await Issue.captureConsole {
+            var config = ExplicitTypeInterfaceConfiguration()
+            try config.apply(configuration: ["invalidKey": "error"])
+        }
+        XCTAssertEqual(
+            console,
             "warning: Configuration for 'explicit_type_interface' rule contains the invalid key(s) 'invalidKey'."
         )
     }

Tests/BuiltInRulesTests/IndentationWidthRuleTests.swift

@@ -8,14 +8,15 @@ final class IndentationWidthRuleTests: SwiftLintTestCase {
         let defaultValue = IndentationWidthConfiguration().indentationWidth
 
         for indentation in [0, -1, -5] {
-            try await AsyncAssertEqual(
-                try await Issue.captureConsole {
-                    var testee = IndentationWidthConfiguration()
-                    try testee.apply(configuration: ["indentation_width": indentation])
-
-                    // Value remains the default.
-                    XCTAssertEqual(testee.indentationWidth, defaultValue)
-                },
+            let console = try await Issue.captureConsole {
+                var testee = IndentationWidthConfiguration()
+                try testee.apply(configuration: ["indentation_width": indentation])
+
+                // Value remains the default.
+                XCTAssertEqual(testee.indentationWidth, defaultValue)
+            }
+            XCTAssertEqual(
+                console,
                 "warning: Invalid configuration for 'indentation_width' rule. Falling back to default."
             )
         }

Tests/BuiltInRulesTests/MultilineParametersConfigurationTests.swift

@@ -6,13 +6,14 @@ import XCTest
 final class MultilineParametersConfigurationTests: SwiftLintTestCase {
     func testInvalidMaxNumberOfSingleLineParameters() async throws {
         for maxNumberOfSingleLineParameters in [0, -1] {
-            try await AsyncAssertEqual(
-                try await Issue.captureConsole {
-                    var config = MultilineParametersConfiguration()
-                    try config.apply(
-                        configuration: ["max_number_of_single_line_parameters": maxNumberOfSingleLineParameters]
-                    )
-                },
+            let console = try await Issue.captureConsole {
+                var config = MultilineParametersConfiguration()
+                try config.apply(
+                    configuration: ["max_number_of_single_line_parameters": maxNumberOfSingleLineParameters]
+                )
+            }
+            XCTAssertEqual(
+                console,
                 """
                 warning: Inconsistent configuration for 'multiline_parameters' rule: Option \
                 'max_number_of_single_line_parameters' should be >= 1.
@@ -22,13 +23,14 @@ final class MultilineParametersConfigurationTests: SwiftLintTestCase {
     }
 
     func testInvalidMaxNumberOfSingleLineParametersWithSingleLineEnabled() async throws {
-        try await AsyncAssertEqual(
-            try await Issue.captureConsole {
-                var config = MultilineParametersConfiguration()
-                try config.apply(
-                    configuration: ["max_number_of_single_line_parameters": 2, "allows_single_line": false]
-                )
-            },
+        let console = try await Issue.captureConsole {
+            var config = MultilineParametersConfiguration()
+            try config.apply(
+                configuration: ["max_number_of_single_line_parameters": 2, "allows_single_line": false]
+            )
+        }
+        XCTAssertEqual(
+            console,
             """
             warning: Inconsistent configuration for 'multiline_parameters' rule: Option \
             'max_number_of_single_line_parameters' has no effect when 'allows_single_line' is false.

Tests/BuiltInRulesTests/NoEmptyBlockConfigurationTests.swift

@@ -23,11 +23,12 @@ final class NoEmptyBlockConfigurationTests: SwiftLintTestCase {
     }
 
     func testInvalidKeyInCustomConfiguration() async throws {
-        try await AsyncAssertEqual(
-            try await Issue.captureConsole {
-                var config = NoEmptyBlockConfiguration()
-                try config.apply(configuration: ["invalidKey": "error"])
-            },
+        let console = try await Issue.captureConsole {
+            var config = NoEmptyBlockConfiguration()
+            try config.apply(configuration: ["invalidKey": "error"])
+        }
+        XCTAssertEqual(
+            console,
             "warning: Configuration for 'no_empty_block' rule contains the invalid key(s) 'invalidKey'."
         )
     }

Tests/FrameworkTests/RuleConfigurationDescriptionTests.swift

@@ -491,35 +491,36 @@ final class RuleConfigurationDescriptionTests: SwiftLintTestCase {
     }
 
     func testDeprecationWarning() async throws {
-        try await AsyncAssertEqual(
-            try await Issue.captureConsole {
-                var configuration = TestConfiguration()
-                try configuration.apply(configuration: ["set": [6, 7]])
-            },
+        let console = try await Issue.captureConsole {
+            var configuration = TestConfiguration()
+            try configuration.apply(configuration: ["set": [6, 7]])
+        }
+        XCTAssertEqual(
+            console,
             "warning: Configuration option 'set' in 'my_rule' rule is deprecated. Use the option 'other_opt' instead."
         )
     }
 
     func testNoDeprecationWarningIfNoDeprecatedPropertySet() async throws {
-        try await AsyncAssertTrue(
-            try await Issue.captureConsole {
-                var configuration = TestConfiguration()
-                try configuration.apply(configuration: ["flag": false])
-            }.isEmpty
-        )
+        let console = try await Issue.captureConsole {
+            var configuration = TestConfiguration()
+            try configuration.apply(configuration: ["flag": false])
+        }
+        XCTAssertTrue(console.isEmpty)
     }
 
     func testInvalidKeys() async throws {
-        try await AsyncAssertEqual(
-            try await Issue.captureConsole {
-                var configuration = TestConfiguration()
-                try configuration.apply(configuration: [
-                    "severity": "error",
-                    "warning": 3,
-                    "unknown": 1,
-                    "unsupported": true,
-                ])
-            },
+        let console = try await Issue.captureConsole {
+            var configuration = TestConfiguration()
+            try configuration.apply(configuration: [
+                "severity": "error",
+                "warning": 3,
+                "unknown": 1,
+                "unsupported": true,
+            ])
+        }
+        XCTAssertEqual(
+            console,
             "warning: Configuration for 'RuleMock' rule contains the invalid key(s) 'unknown', 'unsupported'."
         )
     }