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