Spring Boot Hikari can't find DriverClassName

I think the issue is with dependency scope which is set as test.

Scope test indicates that dependency isn't required at standard runtime of application and should only be used for purpose of test runs only!

Usually database connectors dependency are set with runtime scope.

 <dependency>
    <groupId>com.microsoft.sqlserver</groupId>
    <artifactId>mssql-jdbc</artifactId>
    <version>6.4.0.jre8</version>
    <scope>runtime</scope>
 </dependency>