added unit testing, and started implementing unit tests...phew

node_modules/winston/test/transports/file-tailrolling.test.js

@@ -0,0 +1,93 @@
+/* eslint-disable no-sync */
+const assert = require('assert');
+const rimraf = require('rimraf');
+const fs = require('fs');
+const path = require('path');
+const winston = require('../../lib/winston');
+
+const { MESSAGE } = require('triple-beam');
+
+//
+// Remove all log fixtures
+//
+function removeFixtures(done) {
+  rimraf(path.join(__dirname, '..', 'fixtures', 'logs', 'testtailrollingfiles*'), done);
+}
+
+
+
+let tailrollTransport = null;
+
+describe('winston/transports/file/tailrolling', function () {
+  describe('An instance of the File Transport', function () {
+    before(removeFixtures);
+    after(removeFixtures);
+
+    it('init logger AFTER cleaning up old files', function () {
+      tailrollTransport = new winston.transports.File({
+        timestamp: false,
+        json: false,
+        filename: path.join(__dirname, '..', 'fixtures', 'logs', 'testtailrollingfiles.log'),
+        maxsize: 4096,
+        maxFiles: 3,
+        tailable: true
+      })
+        .on('open', console.log); // eslint-disable-line no-console
+    });
+
+    it('and when passed more files than the maxFiles', function (done) {
+      let created = 0;
+      let loggedTotal = 0;
+
+      function data(ch, kb) {
+        return String.fromCharCode(65 + ch).repeat(kb * 1024 - 1);
+      }
+
+      function logKbytes(kbytes, txt) {
+        const toLog = {};
+	      toLog[MESSAGE] = data(txt, kbytes);
+        tailrollTransport.log(toLog);
+      }
+
+      tailrollTransport.on('logged', function (info) {
+        loggedTotal += info[MESSAGE].length + 1;
+        if (loggedTotal >= 14 * 1024) { // just over 3 x 4kb files
+          return done();
+        }
+
+        if (loggedTotal % 4096 === 0) {
+          created++;
+        }
+        // eslint-disable-next-line max-nested-callbacks
+        setTimeout(() => logKbytes(1, created), 1);
+      });
+
+      logKbytes(1, created);
+    });
+
+    it('should be 3 log files, base to maxFiles - 1', function () {
+      for (var num = 0; num < 4; num++) {
+        const file = !num ? 'testtailrollingfiles.log' : 'testtailrollingfiles' + num + '.log';
+        const fullpath = path.join(__dirname, '..', 'fixtures', 'logs', file);
+
+        if (num === 3) {
+          return assert.ok(!fs.existsSync(fullpath));
+        }
+
+        assert.ok(fs.existsSync(fullpath));
+      }
+
+      return false;
+    });
+
+    it('should have files in correct order', function () {
+      ['D', 'C', 'B'].forEach(function (letter, i) {
+        const file = !i ? 'testtailrollingfiles.log' : 'testtailrollingfiles' + i + '.log';
+        let content = fs.readFileSync(path.join(__dirname, '..', 'fixtures', 'logs', file), 'ascii');
+        content = content.replace(/\s+/g, '');
+
+        assert(content.match(new RegExp(letter, 'g'))[0].length, content.length);
+      });
+    });
+  });
+});