XML schema for Database Unit Tests

Question

I am attempting to develop an XML schema (XSD) to represent a set of unit tests for some code. (Specifically, I am testing Oracle PL/SQL stored procedures.)

I would like to have something that represents:

• the procedure itself
• the data used for each test (both arguments to be supplied to the procedure, and data to be loaded into the database before beginning the test(s))
• the expected result of each test

Each procedure can have multiple tests, but I think I would like to only have the tests for one procedure in each XML file.

Below is the schema I have so far: any comments or suggestions would be welcomed!

<?xml version="1.0" encoding="UTF-8"?>
<schema targetNamespace="http://www.example.com/TestData"
    elementFormDefault="qualified" xmlns="http://www.w3.org/2001/XMLSchema"
    xmlns:tns="http://www.example.com/TestData">
    <complexType name="ProcedureType">
        <complexContent>
            <extension base="tns:AbstractProcedureType">
            </extension>
        </complexContent>
    </complexType>
    <complexType name="FunctionType">
        <complexContent>
            <extension base="tns:AbstractProcedureType">
                <attribute name="ReturnType" type="tns:DataTypeType"></attribute>
            </extension>
        </complexContent>
    </complexType>
    <complexType name="AbstractProcedureType" abstract="true">
        <sequence>
            <element name="PackageName" type="string" minOccurs="0" maxOccurs="1"></element>
            <element name="Name" type="string" minOccurs="1" maxOccurs="1"/>
            <element name="Arguments" type="tns:ArgumentsType"
                minOccurs="1" maxOccurs="1" />
        </sequence>
    </complexType>
    <complexType name="ArgumentType">
        <attribute name="Name" type="string" use="required"/>
        <attribute name="DataType" type="tns:DataTypeType"
            use="required"/>
    </complexType>
    <simpleType name="DataTypeType">
        <restriction base="string">
            <enumeration value="VARCHAR2"/>
            <enumeration value="NUMBER"/>
        </restriction>
    </simpleType>
    <complexType name="TestType">
        <sequence>
            <choice maxOccurs="1" minOccurs="1">
                <element name="Procedure" type="tns:ProcedureType"></element>
                <element name="Function" type="tns:FunctionType"></element>
            </choice>

            <element name="Instance" type="tns:TestInstanceType"></element>
        </sequence>
    </complexType>
    <complexType name="TestInstanceType">
        <sequence>
            <element name="Arguments" type="tns:ArgumentType"
                maxOccurs="unbounded" minOccurs="0">
            </element>
            <element name="ExpectedResult"
                type="tns:ExpectedResultType" maxOccurs="1" minOccurs="1">
            </element>
        </sequence>
    </complexType>
    <complexType name="ExpectedResultType">
        <attribute name="Type" use="required">
            <simpleType>
                <restriction base="string">
                    <enumeration value="value"></enumeration>
                    <enumeration value="exception"></enumeration>
                    <enumeration value="null"></enumeration>
                    <enumeration value="nothing"></enumeration>
                    <enumeration value="query"></enumeration>
                </restriction>
            </simpleType>
        </attribute>
    </complexType>
    <complexType name="ArgumentsType">
        <sequence>
            <element name="Argument" type="tns:ArgumentType" maxOccurs="1" minOccurs="0"></element>
        </sequence>
    </complexType>
    <element name="Tests" type="tns:TestsType"></element>
    <complexType name="TestsType">
        <sequence>
            <element name="Test" type="tns:TestType" maxOccurs="unbounded" minOccurs="0"></element>
        </sequence>
    </complexType>
</schema>

Answer 1

• I would move PackageName and Name elements of the AbstractProcedureType to attributes.
• I don't think you need an AbstractProcedureType, just have a ProcedureType and FunctionType derived from it.
• it's not clear why ArgumentsType may have either 0 or 1 argument... I would say that it should have maxOccurs="unbounded"
• I would make Arguments element optional in ProcedureType and FunctionType (minOccurs="0"), and require at least one argument if the node is present.

Now let's move to global changes...

• Since you want to have a single procedure/function per XML we can move the declaration of procedure right under the root node.
• I removed some of the named complextypes in favor of in-place type definitions
• You can add some referential constraints to XSD (e.g. argument names in test should match procedure/function declaration).

As a result of these changes I've got the following XSD:

<?xml version="1.0" encoding="UTF-8"?>
<schema targetNamespace="http://www.example.com/TestData"
        elementFormDefault="qualified" xmlns="http://www.w3.org/2001/XMLSchema"
        xmlns:tns="http://www.example.com/TestData">
    <element name="Tests" type="tns:TestsType">
        <key name="Argument.Name">
            <selector xpath="tns:Procedure/tns:Arguments/tns:Argument | tns:Function/tns:Arguments/tns:Argument" />
            <field xpath="@Name" />
        </key>
    </element>
    <complexType name="TestsType">
        <sequence>
            <choice maxOccurs="1" minOccurs="1">
                <element name="Procedure" type="tns:ProcedureType" />
                <element name="Function" type="tns:FunctionType" />
            </choice>
            <element name="Test" type="tns:TestInstanceType" minOccurs="0" maxOccurs="unbounded" />
        </sequence>
    </complexType>
    <complexType name="ProcedureType">
        <sequence>
            <element name="Arguments" minOccurs="0" maxOccurs="1">
                <complexType>
                    <sequence>
                        <element name="Argument" minOccurs="0" maxOccurs="unbounded">
                            <complexType>
                                <attribute name="Name" type="string" use="required" />
                                <attribute name="DataType" type="tns:DataTypeType" use="required" />
                            </complexType>
                        </element>
                    </sequence>
                </complexType>
            </element>
        </sequence>
        <attribute name="PackageName" type="string" use="optional" />
        <attribute name="Name" type="string" use="required" />
    </complexType>
    <complexType name="FunctionType">
        <complexContent>
            <extension base="tns:ProcedureType">
                <attribute name="ReturnType" type="tns:DataTypeType" use="required" />
            </extension>
        </complexContent>
    </complexType>
    <simpleType name="DataTypeType">
        <restriction base="string">
            <enumeration value="VARCHAR2" />
            <enumeration value="NUMBER" />
        </restriction>
    </simpleType>
    <complexType name="TestInstanceType">
        <sequence>
            <element name="Argument" minOccurs="0" maxOccurs="unbounded">
                <complexType>
                    <attribute name="Name" type="string" use="required" />
                    <attribute name="Value" type="string" use="required" />
                </complexType>
                <keyref name="Argument.Name.Exists" refer="tns:Argument.Name">
                    <selector xpath="." />
                    <field xpath="@Name" />
                </keyref>
            </element>
            <element name="ExpectedResult" type="tns:ExpectedResultType" maxOccurs="1" minOccurs="1" />
        </sequence>
    </complexType>
    <complexType name="ExpectedResultType">
        <attribute name="Type" use="required">
            <simpleType>
                <restriction base="string">
                    <enumeration value="value" />
                    <enumeration value="exception" />
                    <enumeration value="null" />
                    <enumeration value="nothing" />
                    <enumeration value="query" />
                </restriction>
            </simpleType>
        </attribute>
    </complexType>
</schema>

What I would do next:

• Create several elements for different expected result types (query, exception, etc) and define corresponding attributes and elements on them
• You can also replace generic Argument with typed elements, that will allow you to define even more constraints on values of arguments in tests