Add mocha-json test case for empty test results

__tests__/fixtures/empty/mocha-json.json

@@ -0,0 +1,16 @@
+{
+  "stats": {
+    "suites": 0,
+    "tests": 0,
+    "passes": 0,
+    "pending": 0,
+    "failures": 0,
+    "start": "2021-03-08T20:01:44.391Z",
+    "end": "2021-03-08T20:01:44.391Z",
+    "duration": 0
+  },
+  "tests": [],
+  "pending": [],
+  "failures": [],
+  "passes": []
+}

__tests__/mocha-json.test.ts

@@ -7,6 +7,23 @@ import {getReport} from '../src/report/get-report'
 import {normalizeFilePath} from '../src/utils/path-utils'
 
 describe('mocha-json tests', () => {
+
+  it('produces empty test run result when there are no test cases', async () => {
+    const fixturePath = path.join(__dirname, 'fixtures', 'empty', 'mocha-json.json')
+    const filePath = normalizeFilePath(path.relative(__dirname, fixturePath))
+    const fileContent = fs.readFileSync(fixturePath, {encoding: 'utf8'})
+
+    const opts: ParseOptions = {
+      parseErrors: true,
+      trackedFiles: []
+    }
+
+    const parser = new MochaJsonParser(opts)
+    const result = await parser.parse(filePath, fileContent)
+    expect(result.tests).toBe(0)
+    expect(result.result).toBe('success')
+  })
+
   it('report from ./reports/mocha-json test results matches snapshot', async () => {
     const fixturePath = path.join(__dirname, 'fixtures', 'mocha-json.json')
     const outputPath = path.join(__dirname, '__outputs__', 'mocha-json.md')