Timeline: repair oldest/newest metrics if we fetch nothing

ts/test-node/util/isFileDangerous_test.ts

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+// Copyright 2018-2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { isFileDangerous } from '../../util/isFileDangerous';
+
+describe('isFileDangerous', () => {
+  it('returns false for images', () => {
+    assert.strictEqual(isFileDangerous('dog.gif'), false);
+    assert.strictEqual(isFileDangerous('cat.jpg'), false);
+  });
+
+  it('returns false for documents', () => {
+    assert.strictEqual(isFileDangerous('resume.docx'), false);
+    assert.strictEqual(isFileDangerous('price_list.pdf'), false);
+  });
+
+  it('returns true for executable files', () => {
+    assert.strictEqual(isFileDangerous('run.exe'), true);
+    assert.strictEqual(isFileDangerous('install.pif'), true);
+  });
+
+  it('returns true for Microsoft settings files', () => {
+    assert.strictEqual(isFileDangerous('downl.SettingContent-ms'), true);
+  });
+
+  it('returns false for non-dangerous files that end in ".", which can happen on Windows', () => {
+    assert.strictEqual(isFileDangerous('dog.png.'), false);
+    assert.strictEqual(isFileDangerous('resume.docx.'), false);
+  });
+
+  it('returns true for dangerous files that end in ".", which can happen on Windows', () => {
+    assert.strictEqual(isFileDangerous('run.exe.'), true);
+    assert.strictEqual(isFileDangerous('install.pif.'), true);
+  });
+
+  it('returns false for empty filename', () => {
+    assert.strictEqual(isFileDangerous(''), false);
+  });
+
+  it('returns false for exe at various parts of filename', () => {
+    assert.strictEqual(isFileDangerous('.exemanifesto.txt'), false);
+    assert.strictEqual(isFileDangerous('runexe'), false);
+    assert.strictEqual(isFileDangerous('run_exe'), false);
+  });
+
+  it('returns true for upper-case EXE', () => {
+    assert.strictEqual(isFileDangerous('run.EXE'), true);
+  });
+});