Validate config before loading datastore

tests/validateConfigFile.test.ts

@@ -0,0 +1,40 @@
+import fs = require('fs-extra')
+import os = require('os')
+import path = require('path')
+import validateConfigFile from '../src/datastore/validateConfigFile'
+
+describe('validateConfigFile', () => {
+    let temporaryDirectory: string
+    let configPath: string
+
+    beforeEach(() => {
+        temporaryDirectory = fs.mkdtempSync(
+            path.join(os.tmpdir(), 'caprover-config-')
+        )
+        configPath = path.join(temporaryDirectory, 'config-captain.json')
+    })
+
+    afterEach(() => {
+        fs.removeSync(temporaryDirectory)
+    })
+
+    test('rejects malformed JSON without modifying the file', () => {
+        const malformedConfig = '{"namespace":"captain",}'
+        fs.writeFileSync(configPath, malformedConfig)
+
+        expect(() => validateConfigFile(configPath)).toThrow(
+            'the file contains malformed JSON'
+        )
+        expect(fs.readFileSync(configPath, 'utf8')).toBe(malformedConfig)
+    })
+
+    test('accepts valid JSON', () => {
+        fs.writeJsonSync(configPath, { namespace: 'captain' })
+
+        expect(() => validateConfigFile(configPath)).not.toThrow()
+    })
+
+    test('accepts a missing config file for first-time setup', () => {
+        expect(() => validateConfigFile(configPath)).not.toThrow()
+    })
+})