Adding Environment Variables In Jenkins Using Groovy Script

https://medium.com/@mukeshsingal/access-jenkins-global-environment-variables-using-groovy-or-java-b5c1e6b53685

import hudson.EnvVars;
import hudson.slaves.EnvironmentVariablesNodeProperty;
import hudson.slaves.NodeProperty;
import hudson.slaves.NodePropertyDescriptor;
import hudson.util.DescribableList;
import jenkins.model.Jenkins;public createGlobalEnvironmentVariables(String key, String value){

        Jenkins instance = Jenkins.getInstance();

        DescribableList<NodeProperty<?>, NodePropertyDescriptor> globalNodeProperties = instance.getGlobalNodeProperties();
        List<EnvironmentVariablesNodeProperty> envVarsNodePropertyList = globalNodeProperties.getAll(EnvironmentVariablesNodeProperty.class);

        EnvironmentVariablesNodeProperty newEnvVarsNodeProperty = null;
        EnvVars envVars = null;

        if ( envVarsNodePropertyList == null || envVarsNodePropertyList.size() == 0 ) {
            newEnvVarsNodeProperty = new hudson.slaves.EnvironmentVariablesNodeProperty();
            globalNodeProperties.add(newEnvVarsNodeProperty);
            envVars = newEnvVarsNodeProperty.getEnvVars();
        } else {
            envVars = envVarsNodePropertyList.get(0).getEnvVars();
        }
        envVars.put(key, value)
        instance.save()
}createGlobalEnvironmentVariables('Var1','DummyValue')

MSTest Cheat Sheet

https://www.automatetheplanet.com/mstest-cheat-sheet/