[feat] StreamLogHandler now adds label to log output (#108)

* [feat] StreamLogHandler now adds label to log output
* [test] add test cases for log out format assertion.

Author: prafsoni

Sources/Logging/Logging.swift

@@ -578,6 +578,7 @@ public struct StreamLogHandler: LogHandler {
     }
 
     private let stream: TextOutputStream
+    private let label: String
 
     public var logLevel: Logger.Level = .info
 
@@ -599,6 +600,7 @@ public struct StreamLogHandler: LogHandler {
 
     // internal for testing only
     internal init(label: String, stream: TextOutputStream) {
+        self.label = label
         self.stream = stream
     }
 
@@ -611,7 +613,7 @@ public struct StreamLogHandler: LogHandler {
             : self.prettify(self.metadata.merging(metadata!, uniquingKeysWith: { _, new in new }))
 
         var stream = self.stream
-        stream.write("\(self.timestamp()) \(level):\(prettyMetadata.map { " \($0)" } ?? "") \(message)\n")
+        stream.write("\(self.timestamp()) \(level) \(self.label) :\(prettyMetadata.map { " \($0)" } ?? "") \(message)\n")
     }
 
     private func prettify(_ metadata: Logger.Metadata) -> String? {

Tests/LoggingTests/LoggingTest+XCTest.swift

@@ -42,6 +42,8 @@ extension LoggingTest {
             ("testLogLevelCases", testLogLevelCases),
             ("testLogLevelOrdering", testLogLevelOrdering),
             ("testStreamLogHandlerWritesToAStream", testStreamLogHandlerWritesToAStream),
+            ("testStreamLogHandlerOutputFormat", testStreamLogHandlerOutputFormat),
+            ("testStreamLogHandlerOutputFormatWithMetaData", testStreamLogHandlerOutputFormatWithMetaData),
             ("testStdioOutputStreamFlush", testStdioOutputStreamFlush),
         ]
     }

Tests/LoggingTests/LoggingTest.swift

@@ -451,6 +451,44 @@ class LoggingTest: XCTestCase {
         XCTAssertEqual(interceptStream.strings.count, 1)
     }
 
+    func testStreamLogHandlerOutputFormat() {
+        let interceptStream = InterceptStream()
+        let label = "testLabel"
+        LoggingSystem.bootstrapInternal { _ in
+            StreamLogHandler(label: label, stream: interceptStream)
+        }
+        let log = Logger(label: label)
+
+        let testString = "my message is better than yours"
+        log.critical("\(testString)")
+
+        let pattern = "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(\\+|-)\\d{4}\\s\(Logger.Level.critical)\\s\(label)\\s:\\s\(testString)$"
+
+        let messageSucceeded = interceptStream.interceptedText?.trimmingCharacters(in: .whitespacesAndNewlines).range(of: pattern, options: .regularExpression) != nil
+
+        XCTAssertTrue(messageSucceeded)
+        XCTAssertEqual(interceptStream.strings.count, 1)
+    }
+
+    func testStreamLogHandlerOutputFormatWithMetaData() {
+        let interceptStream = InterceptStream()
+        let label = "testLabel"
+        LoggingSystem.bootstrapInternal { _ in
+            StreamLogHandler(label: label, stream: interceptStream)
+        }
+        let log = Logger(label: label)
+
+        let testString = "my message is better than yours"
+        log.critical("\(testString)", metadata: ["test": "test"])
+
+        let pattern = "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(\\+|-)\\d{4}\\s\(Logger.Level.critical)\\s\(label)\\s:\\stest=test\\s\(testString)$"
+
+        let messageSucceeded = interceptStream.interceptedText?.trimmingCharacters(in: .whitespacesAndNewlines).range(of: pattern, options: .regularExpression) != nil
+
+        XCTAssertTrue(messageSucceeded)
+        XCTAssertEqual(interceptStream.strings.count, 1)
+    }
+
     func testStdioOutputStreamFlush() {
         // flush on every statement
         self.withWriteReadFDsAndReadBuffer { writeFD, readFD, readBuffer in