R2DBC unable to create connection with h2 protocol - spring-boot

Question

I'm trying to leverage H2 for testing and have the following configuration in src/test/resources/application.yaml:
spring:
r2dbc:
url: r2dbc:h2:file://testdb
I have an empty test annotated with #SpringBootTest but when I run it I get the following error:
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [io.r2dbc.pool.ConnectionPool]: Factory method 'connectionFactory' threw exception; nested exception is java.lang.IllegalStateException: Unable to create a ConnectionFactory for 'ConnectionFactoryOptions{options={driver=h2, protocol=file, host=testdb}}'. Available drivers: [ pool, postgresql, h2 ]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:651)
... 131 common frames omitted
Caused by: java.lang.IllegalStateException: Unable to create a ConnectionFactory for 'ConnectionFactoryOptions{options={driver=h2, protocol=file, host=testdb}}'. Available drivers: [ pool, postgresql, h2 ]
at io.r2dbc.spi.ConnectionFactories.get(ConnectionFactories.java:145)
at org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBuilder.build(ConnectionFactoryBuilder.java:125)
at org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryConfigurations.createConnectionFactory(ConnectionFactoryConfigurations.java:56)
at org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryConfigurations$Pool.connectionFactory(ConnectionFactoryConfigurations.java:68)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
... 132 common frames omitted
Here are the relevant dependencies from pom.xml:
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-h2</artifactId>
<version>0.8.4.RELEASE</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>1.4.200</version>
<scope>test</scope>
</dependency>

Answer 1

url: r2dbc:h2:file:///./data/h2db/testdb

Answer 2

Make this change to your application.yml file:
spring:
r2dbc:
url: r2dbc:h2:mem:///testdb #create DB in memory
---
spring:
r2dbc:
url: r2dbc:h2:file:///./testdb #create DB in a file testdb.mv.db