application-profile.yml does not pickup properties from main application.yml - spring-boot

Question

I have a Spring boot application with different environments. I have a main application.yml with a set of properties and an application-test.yml for my test environment.
Inside my application.yml, I have the following config
spring:
liquibase:
enabled: false
user: ${SPRING_DATASOURCE_USERNAME}
password: ${SPRING_DATASOURCE_PASSWORD}
change-log: classpath:db/changelog-master.yaml
And inside my application-test.yml, I have the following
spring
liquibase:
user: sa
password: password
I was expecting my test environment to use liquibase.user and liquibase.password from the application-test.yml and pick the two other sub-properties (liquibase.enabled and liquibase.change-log) from application.yml. My reasoning was that in my test environment, the Application context would pick up all the properties in application.yml and then overwrite only the subkeys defined in application-test.yml, while keeping the original values of application.yml if not explicitly overwritten.
But that does not seem to be the case; it looks as if the key liquibase in my application-test.yml overwrites all the key and subkeys of the liquibase defined in application.yml.
Therefore since in my application-test.yml, liquibase.enabled and liquibase.change-log are not defined; the test environment does not know about these values. I was expecting them to be picked up from the main application.yml instead. I tried to define them manually in my application-test.yml and my tests work fine. If I remove them, my tests fail because they use the default properties for liquibase instead of liquibase.enabled: false and liquibase.change-log: classpath:db/changelog-master.yaml
What I would like to do is the following:
In my main application.yml, have
main_key:
sub_key_1: value_1
sub_key_2: value_2
sub_key_3: value_3
And in my application-test.yml, have only
main_key:
sub_key_1: test_value_1
have my test environment pickup sub_key_2: value_2 and sub_key_3: value_3 directly from application.yml, without them being overwritten by nothing in my test environment (since they are not defined in my application-test.yml)
Is it possible to have think kind of logic : if main_key.sub_key_2 is defined in application-test.yml is defined, then use it, otherwise use the main_key.sub_key_2 defined in application.yml ?
I feel that if I don't define all the sub_keys of my main_key in my application-test.yml, it is not possible to do it.
Many thanks for your help

Answer 1

Actually, I think I know why it does not work.
I had an empty application.yml inside my test/resources/application.yml. So I believe spring boot picks up the test/resources/application.yml instead of the src/main/resources/application.yml when test/resources/application.yml exists.
Which explains why the properties in my src/main/resources/application.yml were not picked up at all.
The solution was simply to delete the test/resources/application.yml