docs(README): add test coverage badge

.gitignore

@@ -10,6 +10,7 @@ node_modules
 
 # tests
 coverage
+test/mocks/testDatabase.sqlite
 # Don't include the compiled main.js file in the repo.
 # They should be uploaded to GitHub releases instead.
 main.js

README.md

@@ -5,6 +5,7 @@ Import all your Apple Books highlights to Obsidian.
 ![Plugin banner](plugin-banner.png)
 
 ![GitHub Downloads](https://img.shields.io/github/downloads/bandantonio/obsidian-apple-books-highlights-plugin/total?style=for-the-badge&logo=github&color=573e7a)
+[![Coveralls](https://img.shields.io/coverallsCoverage/github/bandantonio/obsidian-apple-books-highlights-plugin?branch=master&style=for-the-badge&label=Test%20coverage)](https://coveralls.io/github/bandantonio/obsidian-apple-books-highlights-plugin?branch=master)
 
 ## Overview
 
@@ -138,4 +139,4 @@ Number of annotations:: {{annotations.length}}
 
 Your feedback and ideas are more than welcome and highly appreciated! Join the discussion in the [Obsidian Forum](https://forum.obsidian.md/t/new-plugin-apple-books-import-highlights/76856).
 
-If you have any question, feedback, or issue, feel free to open an issue. 
+If you have any question, feedback, or issue, feel free to open an issue.