21

Data-driven testing

Data-driven testing is a very important aspect of test automation. In short, the goal is to run a given test or set of tests multiple times with different sets of input data and expected results. QF-Test has various means to store data or load external data for use in data-driven tests. The most convenient is based on a 'Data driver' node which sets up an environment for iterating over the sets of data combined with one or more 'Data binder' nodes to bind the variables for test execution. Note that there is no 'Data binder' node as such. The name serves as a generic term for the specific nodes like a 'Data table' or a 'CSV data file'. This is best explained through some examples. A demo test suite with simple and advanced examples named datadriver.qft is provided in the directory doc/tutorial below QF-Test's root directory. Please take care to store modified test suites in a project-related folder.

21.1

Data driver examples

		Figure 21.1:  A simple data-driven test

The image above shows a 'Test set' with a 'Data driver' node that contains a single 'Data binder' in the form of a 'Data table' node. The contents of the 'Data table' are as follows:

		Figure 21.2:  'Data table' example

When the 'Test set' is executed, it will iterate over the rows of the 'Data table' shown above. For each of the three iterations the values of the respective row in the table are bound to the variable named in the matching column header. Thus, during the first iteration the variable named "Model" is bound to "Rolo", "Variant" to "None" and "Price" to "19000". During the second iteration, "Model" is set to "I5" and to "Minigolf" during the third and last iteration. For each iteration, all 'Test case' child nodes of the 'Test set' are run.

The following image shows a run log for the above 'Test set'.

		Figure 21.3:  Run log of a data-driven test

The next example shows that data-driven testing is not limited to a single loop:

		Figure 21.4:  Data-driven test with nested loops

The 'Data driver' now contains a second 'Data table' node with the following contents:

		Figure 21.5:  Second data table example

The 'Test set' will now go through a total of six iterations because for each of the three iterations of the outer loop "cars", both iterations of the inner loop "accessories" will be run as shown in the following run log.

		Figure 21.6:  Run log of a data-driven test with nested loops

Note The extremely useful dynamic names of the loop nodes in the run logs are obtained by setting the attribute 'Name for loop pass in the run log' to the value "car Model: $(Model)"in the first and to "car Model: $(Model), accessory Name: $(Accessory)" in the second example. As you can see, that name is expanded individually for each iteration, so you can make use of the variables bound for that iteration.

21.2

General use of 'Data drivers'

As seen in the example above the 'Data driver' node must be placed in a 'Test set' node, between the optional 'Dependency' and 'Setup' nodes. When the 'Test set' is executed it will check for 'Data driver' and run it. The contents of the 'Data driver' node are not limited to 'Data binders'. Like a normal 'Sequence' the 'Data driver' node can hold any executable node to be able to perform any setup that may be required to retrieve the data. Thus it is also possible to share 'Data binders' by putting them inside a 'Procedure' and calling the 'Procedure' from inside the 'Data driver'.

Conceptually, a 'Data binder' represents a loop where a different set of variables is bound for each iteration. A 'Data binder' must be registered with a name in the 'Data driver' context of a 'Test set'. This ensures that the loop can be interrupted by a 'Break' node with the same name. Once the 'Test set' has run the 'Data driver' node, it will iterate over the registered data loops and perform the tests.

In case of nested loops the 'Data binder' that was registered first represents the outermost loop. Its variables are bound first and have lesser precedence than the variables from the inner loop(s).

21.3

Examples for 'Data drivers'

We provide a couple of examples for reading CSV or Excel files in the test suite doc/tutorial/datadriver.qft.

21.4

Advanced use

Besides the 'Data table' node there are various other means for binding data in a data driver. The 'Excel data file', 'CSV data file', 'Database' and 'Data loop' nodes are all explained in detail in section 40.4.

It is also possible to bind data by calling the 'Procedures' qfs.databinder.bindList or qfs.databinder.bindSets in the standard library qfs.qft. These take as parameters strings with lists or sets of values to split and iterate over. Please see tutorial chapter 8 for information about the standard library.

And finally, data can be bound directly from Jython (and analogous from Groovy and JavaScript) with the help of the databinder module, which offers the following methods:

Some examples:

import databinder

# Three iterations with the values "spam", "bacon" and "eggs"
# bound to the variable named "ingredient"
databinder.bindList(rc, "meal", "ingredient", ["spam", "bacon", "eggs"])
# Same with string values
databinder.bindList(rc, "meal", "ingredient", "spam bacon eggs")
# Same with string values and special separator
databinder.bindList(rc, "meal", "ingredient", "spam|bacon|eggs", "|")

# Two iterations, the first with item="apple" and number="5",
# the second with item="orange" and number="3"
databinder.bindSets(rc, "fruit", ["item", "number"],
                    [["apple",5], ["orange",3]])
# Same with string values, note the linebreak
databinder.bindSets(rc, "fruit", "item number", """apple 5
orange 3""")

# Same as before with the data stored in a dict
databinder.bindDict(rc, "fruit",
                    {"item": ["apple", "orange"],
                     "number": [5,3]})

Last update: 10/11/2023 Copyright © 1999-2023 Quality First Software GmbH