Custom Metadata Type:

Custom Metadata Type Data:

Sample Apex class and test class:

public class Sample {

    public static Sample__mdt getSampleValue( String strName ) {
    
        return [ SELECT DeveloperName, Description__c FROM Sample__mdt WHERE DeveloperName =: strName ];
        
    }

}

@isTest
public class SampleTest {

    static testMethod void test() {
    
        Sample__mdt objSample = Sample.getSampleValue('Test');
        system.assertEquals('Test', objSample.DeveloperName);
        system.assertEquals('Test', objSample.Description__c);
        
    }

}

Output: