chore(test): improve test coverage for fileSyncAppender

appenders/fileSync.js - Line 58 - throw new Error(`maxLogSize (${maxLogSize}) should be > 0`);

lib/appenders/fileSync.js

@@ -51,19 +51,15 @@ function touchFile(file, options) {
 }
 
 class RollingFileSync {
-  constructor(filename, size, backups, options) {
+  constructor(filename, maxLogSize, backups, options) {
     debug('In RollingFileStream');
 
-    function throwErrorIfArgumentsAreNotValid() {
-      if (!filename || !size || size <= 0) {
-        throw new Error('You must specify a filename and file size');
-      }
+    if (maxLogSize < 0) {
+      throw new Error(`maxLogSize (${maxLogSize}) should be > 0`);
     }
 
-    throwErrorIfArgumentsAreNotValid();
-
     this.filename = filename;
-    this.size = size;
+    this.size = maxLogSize;
     this.backups = backups;
     this.options = options;
     this.currentSize = 0;

test/tap/fileSyncAppender-test.js

@@ -61,6 +61,28 @@ test("log4js fileSyncAppender", batch => {
     t.end();
   });
 
+  batch.test("should give error if invalid maxLogSize", async t => {
+    const maxLogSize = -1;
+    const expectedError = new Error(`maxLogSize (${maxLogSize}) should be > 0`);
+    t.throws(
+      () => 
+        log4js.configure({
+          appenders: {
+            file: {
+              type: "fileSync",
+              filename: path.join(__dirname, "fa-invalidMaxFileSize-sync-test.log"),
+              maxLogSize: -1
+            }
+          },
+          categories: {
+            default: { appenders: ["file"], level: "debug" }
+          }
+        }),
+      expectedError
+    );
+    t.end();
+  });
+
   batch.test("with a max file size and no backups", t => {
     const testFile = path.join(__dirname, "/fa-maxFileSize-sync-test.log");
     const logger = log4js.getLogger("max-file-size");