The blog post by Gleb Bahmutov explains how end-to-end tests can effectively cover a significant portion of an application's code using the Cypress framework, and how these tests are integrated with GitLab CI to display code coverage results. It describes a specific example using the cypress-example-todomvc-redux repository, where a single test achieved 72.6% code coverage and illustrates how the coverage report can be viewed as a static HTML site. Bahmutov explains how additional end-to-end tests and unit tests can help reach almost complete code coverage and provides details on setting up GitLab CI to run these tests and display coverage summaries. The post also outlines the configuration needed to cache npm modules and Cypress binaries, run tests, and handle artifacts, including publishing the coverage report as a static site using GitLab Pages. The process ensures that both the coverage number and detailed HTML reports are accessible for review, enabling developers to maintain high code quality through comprehensive test coverage.