Add unit test

Author: Tatyana Kostromskaya

test/units/toolTests.ts

@@ -132,6 +132,29 @@ describe('Tool Tests', function () {
         });
     });
 
+    it('different content-length and file size on disk', async function() {
+        const headers: nock.ReplyHeaders = { 'content-length': '200' };
+        nock('https://microsoft.com')
+            .get('/bytes/36')
+            .reply(200, {
+                username: 'bad',
+                password: 'size'
+            }, headers);
+
+        return new Promise<void>(async(resolve, reject)=> {
+            try {
+                let errorCodeUrl: string = "https://microsoft.com/bytes/36";
+                let downPath: string = await toolLib.downloadTool(errorCodeUrl);
+
+                reject('content-length of file and size of file on disk should not match, but they do');
+            } 
+            catch (err){
+                assert.equal(err.message, `Content-Length (200 bytes) did not match downloaded file size (36 bytes).`);
+                resolve();
+            }
+        });
+    });
+
     it('works with redirect code 302', async function () {
         nock('https://microsoft.com') 
             .get('/redirect-to')

tool.ts

@@ -259,7 +259,8 @@ export async function downloadTool(
                         if (!isNaN(downloadedContentLength) &&
                             !isNaN(fileSizeInBytes) &&
                             fileSizeInBytes !== downloadedContentLength) {
-                            reject(new Error(`Content-Length (${downloadedContentLength} bytes) did not match downloaded file size (${fileSizeInBytes} bytes).`));
+                            let err: Error = new Error(`Content-Length (${downloadedContentLength} bytes) did not match downloaded file size (${fileSizeInBytes} bytes).`);
+                            reject(err);
                         }
 
                         resolve(destPath);