test for issue #3

Author: noogen

package.json

@@ -30,12 +30,12 @@
     "compare",
     "compare-files"
   ],
-  "dependencies": {},
   "devDependencies": {
     "@types/node": "^14.14.21",
     "ava": "^3.15.0",
     "cross-env": "^7.0.3",
     "debug": "^4.3.1",
+    "memory-streams": "^0.1.3",
     "nyc": "^15.1.0",
     "ts-node": "^9.1.1",
     "typescript": "^4.1.3",

tests/empty.txt

@@ -34,3 +34,26 @@ test('test skip header', async t => {
   await m.diff('tests/file1.txt', 'tests/file2.txt');
   t.is(actual, expected);
 });
+
+test('test against null or empty file', async t => {
+  let expected = '-some,csv,data\n';
+
+  const m = new TextFileDiff({
+    skipHeader: false
+  });
+  let actual = '';
+  m.on('-', line => {
+    actual += '-' + line + '\n';
+  });
+
+  m.on('+', line => {
+    actual += '+' + line + '\n';
+  });
+  await m.diff('tests/lowercase.txt', 'tests/empty.txt');
+  t.is(actual, expected, 'faile test empty');
+
+  actual = '';
+  expected = '+null\n-some,csv,data\n';
+  await m.diff('tests/lowercase.txt', 'tests/null.txt');
+  t.is(actual, expected, 'fail test null');
+});

tests/index.js

@@ -0,0 +1 @@
+some,csv,data

tests/lowercase.txt

@@ -0,0 +1 @@
+null