fix(logging): create log file if it doesn't exist (#3202)

Author: phantumcode

AmplifyPlugins/Logging/Sources/AWSCloudWatchLoggingPlugin/Persistence/LogActor.swift

@@ -29,6 +29,7 @@ actor LogActor {
     }
 
     private func write(_ data: Data) throws {
+        try rotation.ensureFileExists()
         if rotation.currentLogFile.hasSpace(for: data) {
             try rotation.currentLogFile.write(data: data)
         } else {

AmplifyPlugins/Logging/Sources/AWSCloudWatchLoggingPlugin/Persistence/LogRotation.swift

@@ -98,6 +98,12 @@ final class LogRotation {
                                  index: 0,
                                  fileSizeLimitInBytes: fileSizeLimitInBytes)
     }
+    
+    func ensureFileExists() throws {
+        if !FileManager.default.fileExists(atPath: currentLogFile.fileURL.relativePath) {
+            try rotate()
+        }
+    }
 
     /// - Returns: A UInt representing the best guess to which index to use
     ///            next when the number of log files is less that the limit

AmplifyPlugins/Logging/Tests/AWSCloudWatchLoggingPluginTests/LogActorTests.swift

@@ -127,4 +127,24 @@ final class LogActorTests: XCTestCase {
         logs = try await systemUnderTest.getLogs()
         XCTAssertEqual(logs.count, 2)
     }
+    
+    /// Given: a Log file
+    /// When: LogActor writes to a log file that doesn't exist
+    /// Then: the log file is created and the log entry is recorded
+    func testLogActorCreatesLogFileIfItDoesNotExist() async throws {
+        let files = try FileManager.default.contentsOfDirectory(at: directory, includingPropertiesForKeys: nil)
+        let fileURL = try XCTUnwrap(files.first)
+        try FileManager.default.removeItem(at: fileURL)
+        var logs = try await systemUnderTest.getLogs()
+        XCTAssertEqual(logs.count, 0)
+        
+        let entry = LogEntry(category: "LogActorTests", namespace: nil, level: .error, message: UUID().uuidString, created: .init(timeIntervalSince1970: 0))
+        try await systemUnderTest.record(entry)
+        try await systemUnderTest.synchronize()
+        
+        logs = try await systemUnderTest.getLogs()
+        XCTAssertEqual(logs.count, 1)
+        let contents = try XCTUnwrap(FileManager.default.contents(atPath: fileURL.path))
+        XCTAssertNotNil(contents)
+    }
 }