Using mockFor to mock Sql.call() in a groovy unit test - unit-testing

Question

I'm trying to mock newInstance() and call() in groovy.sql.Sql:
package com.sample
import grails.test.GrailsUnitTestCase
import groovy.mock.interceptor.MockFor
import groovy.sql.Sql
class MySampleTests extends GrailsUnitTestCase {
void testThat_SqlCall_IsInvokedWithexpectedQuery() {
def mockSql = new MockFor(Sql.class)
mockSql.demand.newInstance { def datasource->
return mockSql
}
mockSql.demand.call { def sql ->
return 0
}
mockSql.use {
MySample targetObject = new MySample()
targetObject.myMethod()
}
}
}
Where this is the target code:
package com.sample
import groovy.sql.Sql
class MySample {
def dataSource
def myMethod() {
def conn = Sql.newInstance(dataSource)
conn.call("test")
}
}
It errs out with:
groovy.lang.MissingMethodException: No signature of method: groovy.mock.interceptor.MockFor.call() is applicable for argument types: (java.lang.String) values: [test]
The error makes it seem like the call() method is not being mocked. Is that the case? What's a fix for it?

Answer 1

Replacing mockSql.demand.call with mockSql.metaClass.call provides a mocked method, but requires manual verification that the method is called, and of the parameter values:
package com.sample
import grails.test.GrailsUnitTestCase
import groovy.mock.interceptor.MockFor
import groovy.sql.Sql
class MySampleTests extends GrailsUnitTestCase {
void testThat_SqlCall_IsInvokedWithexpectedQuery() {
def mockSql = new MockFor(Sql.class)
def callInvoked = 0
mockSql.demand.newInstance { def datasource->
return mockSql
}
mockSql.metaClass.call { def sql ->
assert sql == "test"
++callInvoked
return 0
}
mockSql.use {
MySample targetObject = new MySample()
targetObject.myMethod()
}
assert callInvoked == 1
}
}
I don't know enough groovy yet to understand why this is the case, but it solved the issue for me.
Additional cosmetic changes plus moving the targetObject instantiation out of mySql.use {} result in:
package com.sample
import grails.test.GrailsUnitTestCase
import groovy.mock.interceptor.MockFor
import groovy.sql.Sql
class MySampleTests extends GrailsUnitTestCase {
MySample targetObject = new MySample()
void testThat_SqlCall_IsInvokedWithexpectedQuery() {
def mockSql = new MockFor(Sql)
def callInvoked = 0
mockSql.demand.newInstance { datasource->
mockSql
}
mockSql.metaClass.call { sql ->
assert sql == "test"
++callInvoked
0
}
mockSql.use {
targetObject.myMethod()
}
assert callInvoked == 1
}
}