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Groovy example source code file (CovariantReturnTest.groovy)

This example Groovy source code file (CovariantReturnTest.groovy) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

a, arraylist, b, base, base, baseclass, baseclass, child, child, derivedclass, groovychildimpl, groovychildimpl, list, string

The Groovy CovariantReturnTest.groovy source code

/*
 * Copyright 2003-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package gls.invocation

import gls.CompilableTestSupport

public class CovariantReturnTest extends CompilableTestSupport {

    void testCovariantReturn() {
        assertScript """
            class A {
                Object foo() {1}
            }
            class B extends A{
                String foo(){"2"}
            }
            def b = new B();
            assert b.foo()=="2"
            assert B.declaredMethods.findAll{it.name=="foo"}.size()==2
        """
    }

    void testCovariantReturnOverwritingAbstractMethod() {
        assertScript """
            abstract class Numeric {
                abstract Numeric eval();
            }
            class Rational extends Numeric {
                Rational eval() {this}
            }
            assert Rational.declaredMethods.findAll{it.name=="eval"}.size()==2
        """
    }

    void testCovariantReturnOverwritingObjectMethod() {
        shouldNotCompile """
            class X {
                Long toString() { 333L }
                String hashCode() { "hash" }
            }
        """
    }

    void testCovariantOverwritingMethodWithPrimitives() {
        assertScript """
            class Base {
                Object foo(boolean i) {i}
            }
            class Child extends Base {
                String foo(boolean i) {""+super.foo(i)}
            }
            def x = new Child()
            assert x.foo(true) == "true"
            assert x.foo(false) == "false"
        """
    }

    void testCovariantOverwritingMethodWithInterface() {
        assertScript """
            interface Base {
                List foo()
                Base baz()
            }
            interface Child extends Base {
                ArrayList foo()
                Child baz()
            }
            class GroovyChildImpl implements Child {
                ArrayList foo() {}
                GroovyChildImpl baz() {}
            }
            def x = new GroovyChildImpl()
            x.foo()
            x.baz()
        """
    }

    void testCovariantOverwritingMethodWithInterfaceAndInheritance() {
        assertScript """
            interface Base {
                List foo()
                List bar()
            Base baz()
            }
            interface Child extends Base {
                ArrayList foo()
            }
            class MyArrayList extends ArrayList { }
            class GroovyChildImpl implements Child {
                MyArrayList foo() {}
                MyArrayList bar() {}
                GroovyChildImpl baz() {}
            }
            def x = new GroovyChildImpl()
            x.foo()
            x.bar()
            x.baz()
        """
    }

    void testCovariantMethodFromParentOverwritingMethodFromInterfaceInCurrentclass() {
        assertScript """
            interface I {
                def foo()
            }
            class A {
                String foo(){""}
            }
            class B extends A implements I{}
            def b = new B()
            assert b.foo() == ""
        """

        // basically the same as above, but with an example
        // from an error report (GROOVY-2582)
        // Properties has a method "String getProperty(String)", this class
        // is also a GroovyObject, meaning a "Object getProperty(String)" method
        // should be implemented. But this method should not be the usual automatically
        // added getProperty, but a bridge to the getProperty method provided by Properties
        assertScript """
            class Configuration extends java.util.Properties {}
            assert Configuration.declaredMethods.findAll{it.name=="getProperty"}.size() == 1
            def conf = new Configuration()
            conf.setProperty("a","b")
            // the following assert would fail if standard getProperty method was added
            // by the compiler
            assert conf.getProperty("a") == "b"
        """
    }

    void testImplementedInterfacesNotInfluencing() {
        // in GROOVY-3229 some methods from Appendable were not correctly recognized
        // as already being overriden (PrintWriter<Writer

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