*********************************************** PBBT -- Pluggable Black-Box Testing toolkit *********************************************** .. contents:: Table of Contents Overview ======== PBBT is a regression test harness for *black-box testing*. It is suitable for testing complex software components with well-defined input and output interfaces. :: input +----------+ output o--------> | Software | --------->o +----------+ In black-box testing, a *test case* is a combination of *input* and expected *output* data. The test harness executes the software with the given input and verifies that the produced output coincides with the expected output. Black-box testing could be implemented for many different types of software. For example, * *a database system:* the input is a SQL statement, the output is a set of records; * *a web service:* the input is an HTTP request, the output is an HTTP response; * *a command-line utility:* the input is a sequence of command-line parameters and ``stdin``, the output is ``stdout``; * *a GUI application:* different approaches are possible; for instance, the input could be a sequence of user actions, and the output could be the state of a particular widget. PBBT is a Python library and an application which allows you to: * use built-in test types for testing command-line scripts and Python code; * register custom test types; * prepare test input in a succinct YAML_ format; * in the *train* mode, run the test cases and record expected output; * in the *check* mode, run the test cases and verify that the produced output coincides with the pre-recorded expected output. PBBT is a free software released under MIT license. PBBT is created by Clark C. Evans and Kirill Simonov from `Prometheus Research, LLC`_. Using PBBT ========== To install PBBT, you can use pip_ package manager:: # pip install pbbt This command downloads and installs the latest version of PBBT from `Python Package Index`_. After successful installation, you should be able to import ``pbbt`` Python module and run ``pbbt`` command-line utility. To start using PBBT, you need to create a file with input data. For example, create ``input.yaml`` with the following content:: py: | print "Hello, World!" This file is in YAML_ format, which is a data serialization language similar to JSON_, and, in fact, a superset of JSON. The file above could be represented in JSON as:: { "py": "print \"Hello, World!\"\n" } For description of YAML syntax and semantics, see http://yaml.org/. Next, execute PBBT in *training* mode to generate expected output data. Run:: $ pbbt input.yaml output.yaml --train and accept new output when asked. PBBT will write output data to ``output.yaml``:: py: print-hello-world stdout: | Hello, World! Now you can start PBBT in *checking* mode, in which it executes test cases and verifies that expected and actual output data coincide:: $ pbbt input.yaml output.yaml To add more test cases to ``input.yaml``, you need to convert it to a *test suite*:: title: My Tests tests: - py: | print "Hello, World!" - sh: echo Hello, World! The file now contains a test suite *My Tests* with two test cases: one as in the previous example, and another that executes a shell command ``echo Hello, World!``:: sh: echo Hello, World! The output of this test case is ``stdout`` produced by the shell command. To record expected output, run ``pbbt`` in training mode again. Built-in Test Types =================== Out of the box, PBBT supports a small set of predefined test types: * test Python code; * test a shell command; * file manipulation tests. Also available are special test types: * test suite; * include; * conditional variables. * gateway to other test systems. Each test type defines the structure of input and output records, that is, the set of mandatory and optional fields and the type of field values. In this section, we list all available test types and describe their input fields. Common Fields ------------- The following optional fields are available for all test types where they make sense: ``skip``: ``true`` or ``false`` On ``true``, skip this test case. ``if``: variable, list of variables or Python expression On a *variable name*, run this test case only if the variable is defined and not false. On a *list of variables*, run this test case only if at least one variable is defined and not false. On a *Python expression*, run this test case if the expression evaluates to true. You can use any conditional variables in the expression. ``unless``: variable, list of variables or Python expression On a *variable name*, skip this test case if the variable is defined and not false. On a *list of variables*, skip this test case if at least one variable is defined and not false. On a *Python expression*, skip this test case if the expression evaluates to true. You can use any conditional variables in the expression. ``ignore``: ``true``, ``false`` or regular expression On ``true``, permit the actual and expected output to be unequal. The test case must still execute without any errors. On a *regular expression*, pre-process the actual and expected output before comparing them: 1. Run the regular expression against the output data and find all matches. 2. If the regular expression does not contain ``()`` subgroups, erase all the matches from the output. 3. If the regular expression contains one or more ``()`` subgroups, erase the content of the subgroups from the output. The regular expression is compiled with ``MULTILINE`` and ``VERBOSE`` flags. Example:: title: Integration with MySQL if: has_mysql tests: - set: MYSQL_HOST: localhost MYSQL_PORT: 3306 unless: [MYSQL_HOST, MYSQL_PORT] - read: /etc/mysql/my.cnf if: MYSQL_HOST == 'localhost' - py: test-scalar-types.py ignore: | ^Today:.(\d\d\d\d)-(\d\d)-(\d\d)$ - py: test-array-types.py skip: true # No array type in MySQL Test Suite ---------- A test suite is a collection of test cases. A suite may contain other suites and thus all test suites form a tree structure. A *path* formed from suite identifiers can uniquely locate any suite. We use file-system notation for suite paths (e.g. ``/path/to/suite``). Fields: ``title``: text The title of the suite. ``suite``: identifier (optional) The identifier of the suite. If not set, generated from the title. ``tests``: list of input records The content of the suite. ``output``: path (optional) If set, the expected output of the suite is loaded from the given file. Example:: title: All Tests suite: all output: output.yaml tests: - py: ./test/core.py - py: ./test/ext.py - title: Database Tests tests: - py: ./test/sqlite.py - py: ./test/pgsql.py - py: ./test/mysql.py In this example, the path to the *Database Tests* suite is ``/all/database-tests``. Conditional Variables --------------------- This test case defines a conditional variable. Variables could be used in ``if`` and ``unless`` clauses to conditionally enable or disable a test case. Variables could also be set or read in Python tests via a global dictionary ``__pbbt__``. Conditional variables could also be set from command line using ``-D`` option. Setting a conditional variable affects all subsequent test cases within the same test suite. Variable values are reset on exit from the suite. Fields: ``set``: variable or dictionary of variables On a *variable name*, set the value of the given variable to ``True``. On a *dictionary*, set the values of the given variables. Example:: title: MySQL Tests tests: - set: MYSQL - set: MYSQL_HOST: localhost MYSQL_PORT: 3306 unless: [MYSQL_HOST, MYSQL_PORT] - py: | # Determine the version of the MySQL server import MySQLdb connection = MySQLdb.connect(host=__pbbt__['MYSQL_HOST'], port=int(__pbbt__['MYSQL_PORT']), db='mysql') cursor = connection.cursor() cursor.execute("""SELECT VERSION()""") version_string = cursor.fetchone()[0] version = tuple(map(int, version_string.split('-')[0].split('.'))) __pbbt__['MYSQL_VERSION'] = version - py: test-ddl.py - py: test-dml.py - py: test-select.py - py: test-new-features.py if: MYSQL_VERSION >= (5, 5) Include Test ------------ This test case loads and executes a test case from a file. Fields: ``include``: path The file to load. The file should contain an input test record in YAML format. Example:: title: All Tests tests: - include: test/core.yaml - include: test/ext.yaml - include: test/sqlite.yaml - include: test/pgsql.yaml - include: test/mysql.yaml Python Code ----------- This test case executes Python code and produces ``stdout``. Fields: ``py``: path or Python code On *Python code*, the source code to execute. On a *file name*, the file which contains source code to execute. ``stdin``: text (optional) Content of the standard input. ``except``: exception type (optional) If set, indicates that the code is expected to raise an exception of the given type. Example:: title: Python tests tests: - py: hello.py - py: &sum | # Sum of two numbers import sys a = int(sys.stdin.readline()) b = int(sys.stdin.readline()) c = a+b sys.stdout.write("%s\n" % c) stdin: | 2 2 - py: *sum stdin: | 1 -5 - py: *sum stdin: | one three except: ValueError Note that we use a YAML anchor (denoted by ``&sum``) and aliases (denoted by ``*sum``) to use the same piece of code in several tests. Shell Command ------------- This test case executes a shell command and produces ``stdout``. Fields: ``sh``: command or executable with a list of parameters The shell command to execute. ``stdin``: text (optional) Content of the standard input. ``cd``: path (optional) Change the current working directory to the given path before executing the command. ``environ``: dictionary of variables (optional) Add the given variables to the command environment. ``exit``: integer (optional) The expected exit code; ``0`` by default. Example:: title: Shell tests tests: - sh: echo Hello, World! - sh: cat stdin: | Hello, World! - sh: [cat, /etc/shadow] exit: 1 # Permission denied Write to File ------------- This test case creates a file with the given content. Fields: ``write``: path The file to create. ``data``: text The file content. Example:: write: test/tmp/data.txt data: | Hello, World! Read from File -------------- The output of this test is the content of a file. Fields: ``read``: path The file to read. Example:: read: test/tmp/data.txt Remove File ----------- This test case removes a file. It is not an error if the file does not exist. Fields: ``rm``: path or list of paths File(s) to remove. Example:: rm: test/tmp/data.txt Make Directory -------------- This test case creates a directory. Parent directories are also created if necessary. It is not an error if the directory already exists. Fields: ``mkdir``: path The directory to create. Example:: mkdir: test/tmp Remove Directory ---------------- This test case removes a directory with all its content. It is not an error if the directory does not exist. Fields: ``rmdir``: path The directory to delete. Example:: rmdir: test/tmp Doctest ------- This test case executes ``doctest`` on a set of files. Fields: ``doctest``: path pattern Files with doctest sessions. Example:: doctest: test/test_*.rst Unittest -------- This test case executes ``unittest`` test suite. Fields: ``unittest``: path pattern Files with unittest tests. Example:: unittest: test/test_*.py Pytest ------ This test case executes ``py.test`` test suite. Package ``pytest`` from http://pytest.org/ must be installed. Fields: ``pytest``: path pattern Files with py.test tests. Example:: pytest: test/test_*.py Coverage -------- This test case starts coverage of Python code. Package ``coverage`` from http://nedbatchelder.com/code/coverage/ must be installed. Fields: ``coverage``: file name or ``None`` Path to the configuration file. ``data_file``: file name Where to save coverage data. ``timid``: ``false`` or ``true`` (optional) Use a simpler trace function. ``branch``: ``false`` or ``true`` (optional) Enable branch coverage. ``source``: file paths of package names (optional) Source files or packages to measure. ``include``: file patterns Files to measure. ``omit``: file patterns Files to omit. Example:: coverage: source: pbbt branch: true Coverage check -------------- This test case stops coverage and reports measurement summary. Fields: ``coverage-check``: float Expected coverage percentage. Example:: coverage-check: 99.0 Coverage report --------------- This test case stops coverage and saves coverage report to a file. Fields: ``coverage-report``: directory Where to save the report. Example:: coverage-report: coverage Custom Test Types ================= In this section, we discuss how to add custom test types to PBBT. Suppose we want to test a SQL database by running a series of SQL queries and validating that we get expected output. To implement this testing scheme, we need a way to: * open a connection to the database; * execute a SQL statement and produce a sequence of records. The input file may look like this:: title: Database tests tests: # Remove the database file left after the last testing session. - rm: test.sqlite # Create a new SQLite database. - connect: test.sqlite # Run a series of SQL commands. - sql: | SELECT 'Hello, World!'; - sql: | CREATE TABLE student ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, gender CHAR(1) NOT NULL CHECK (gender in ('f', 'i', 'm')), dob DATE NOT NULL ); - sql: | INSERT INTO student (id, name, gender, dob) VALUES (1001, 'Linda Wright', 'f', '1988-10-03'), (1002, 'Beth Thompson', 'f', '1988-01-24'), (1003, 'Mark Melton', 'm', '1984-06-05'), (1004, 'Judy Flynn', 'f', '1986-09-02'), (1005, 'Jonathan Bouchard', 'm', '1982-02-12'); - sql: | SELECT * FROM student ORDER BY dob; - sql: | SELECT name FROM student WHERE id = 1003; In this input file, we use two new types of test cases: ``connect`` Specifies the connection to a SQLite database. ``sql`` Specifies a SQL statement to execute. We will write a PBBT extension implementing these test types. Create a file ``sql.py`` with the following content:: from pbbt import Test, Field, BaseCase, MatchCase, listof import sqlite3, traceback, csv, StringIO @Test class ConnectCase(BaseCase): class Input: connect = Field(str) def check(self): self.state['connect'] = None try: self.state['connect'] = sqlite3.connect(self.input.connect) except: self.ui.literal(traceback.format_exc()) self.ui.warning("exception occurred while" " connecting to the database") self.ctl.failed() else: self.ctl.passed() @Test class SQLCase(MatchCase): class Input: sql = Field(str) class Output: sql = Field(str) rows = Field(listof(listof(object))) def render(self, output): stream = StringIO.StringIO() writer = csv.writer(stream, lineterminator='\n') writer.writerows(output.rows) return stream.getvalue() def run(self): connection = self.state.get('connect') if not connection: self.ui.warning("database connection is not defined") return rows = [] try: cursor = connection.cursor() cursor.execute(self.input.sql) for row in cursor.fetchall(): rows.append(list(row)) except: self.ui.literal(traceback.format_exc()) self.ui.warning("exception occurred while" " executing a SQL query") connection.rollback() new_output = None else: connection.commit() new_output = self.Output(sql=self.input.sql, rows=rows) return new_output To use this extension, add parameter ``-E sql.py`` to all PBBT invocations. For example:: $ pbbt -E sql.py input.yaml output.yaml --train Now we will explain the content of ``sql.py`` line by line. The first line imports some classes and decorators we will use:: from pbbt import Test, Field, BaseCase, MatchCase To register a test type, use ``@Test`` decorator. Here is a most general template:: @Test class CustomCase(object): class Input: some_field = Field(...) [...] class Output: some_field = Field(...) [...] def __init__(self, ctl, input, output): self.ctl = ctl self.input = input self.output = output def __call__(self): [...] return new_output The argument of the decorator must be a class that adheres the following rules: * The structure of input and output records is described with nested classes ``Input`` and ``Output``. Record fields are specified using ``Field`` descriptor. * To create a test case, the test harness makes an instance of the class. The class constructor accepts three arguments: ``ctl`` Test harness controller. It is used for user interaction, reporting test success or failure, and as a storage for conditional variables. ``input`` The input record. ``output`` The expected output record or ``None``. * The test case is executed by calling its ``__call__()`` method. This method must run the test case, generate a new output record, and compare it with the given expected output record. If the expected and actual output record do not coincide: * In the *check* mode, the method must report a failure. * In the *train* mode, the method may ask the user for permission to update expected output. If expected output is to be updated, the method should return the new output record. PBBT also provides two mixin classes: ``BaseCase`` and ``MatchCase``. These classes implement most of the necessary functionality for common types of tests. Let's review ``connect`` test type, which is implemented by ``ConnectCase`` class:: @Test class ConnectCase(BaseCase): class Input: connect = Field(str) def check(self): [...] ``ConnectCase`` is inherited from ``BaseCase``, which is suitable for test which produce no output data and are executed for their side effects. The nested ``Input`` class definition is used to declare the fields of the input record. In this case, the input record has just one text field ``connect``, which contains the name of the database. Test types inherited from ``BaseCase`` must override abstract method ``check()``:: import sqlite3, traceback [...] @Test class ConnectCase(BaseCase): [...] def check(self): self.state['connect'] = None try: self.state['connect'] = sqlite3.connect(self.input.connect) except: self.ui.literal(traceback.format_exc()) self.ui.warning("exception occurred while" " connecting to the database") self.ctl.failed() else: self.ctl.passed() This code attempts to create a new database connection and store it as a conditional variable ``connect``. If the attempt fails, it calls ``ui.literal()`` to display the exception traceback and ``ctl.failed()`` to report test failure. Otherwise, ``ctl.passed()`` is called to indicate that the test succeeded. Next, let's review ``sql`` test type:: @Test class SQLCase(MatchCase): class Input: sql = Field(str) class Output: sql = Field(str) rows = Field(listof(listof(object))) def run(self): [...] def render(self, output): [...] This test type has both input and output records, which are described with ``Input`` and ``Output`` nested classes. The input record contains one field ``sql``, a SQL query to execute. The output record contains two fields: ``sql`` and ``rows``. Field ``sql`` contains the same SQL query and is used for matching the output record with the complementary input record. Field ``rows`` contains a list of output rows generated by the SQL query. ``SQLCase`` is inherited from ``MatchCase``, which is a mixin class for test types that produce text output. Test types inherited from ``MatchCase`` must override two methods: ``run()`` Executes the test case and returns the produced output record. ``render(output)`` Convert an output record to printable form. In ``SQLCase``, ``render()`` is implemented by converting output rows to CSV format:: import csv, StringIO [...] @Test class SQLCase(MatchCase): [...] def render(self, output): stream = StringIO.StringIO() writer = csv.writer(stream, lineterminator='\n') writer.writerows(output.rows) return stream.getvalue() Method ``run()`` is implemented as follows:: @Test class SQLCase(MatchCase): [...] def run(self): connection = self.state.get('connect') if not connection: self.ui.warning("database connection is not defined") return rows = [] try: cursor = connection.cursor() cursor.execute(self.input.sql) for row in cursor.fetchall(): rows.append(list(row)) except: self.ui.literal(traceback.format_exc()) self.ui.warning("exception occurred while" " executing a SQL query") connection.rollback() new_output = None else: connection.commit() new_output = self.Output(sql=self.input.sql, rows=rows) return new_output Command-line Interface ====================== Usage:: pbbt [<options>] INPUT [OUTPUT] Here, ``INPUT`` and ``OUTPUT`` are files which contain input and output test data respectively. The following options are available: ``-h``, ``--help`` Display usage information and exit. ``-q``, ``--quiet`` Show only warnings and errors. ``-T``, ``--train`` Run tests in the training mode. ``-P``, ``--purge`` Purge stale output data. ``-M N``, ``--max-errors N`` Halt after ``N`` tests failed; ``0`` means "never". ``-D VAR``, ``-D VAR=VALUE``, ``--define VAR``, ``--define VAR=VALUE`` Set a conditional variable. ``-E FILE``, ``-E MODULE``, ``--extend FILE``, ``--extend MODULE`` Load a PBBT extension from a file or a Python module. ``-S ID``, ``--suite ID`` Run a specific test suite. PBBT can also read configuration from the following files: ``setup.cfg`` This file is in INI format with PBBT settings defined in section ``[pbbt]``. The following parameters are recognized: ``extend``, ``input``, ``output``, ``define``, ``suite``, ``train``, ``purge``, ``max_errors``, ``quiet``. ``pbbt.yaml`` This file must be a YAML file with the following keys: ``extend``, ``input``, ``output``, ``define``, ``suite``, ``train``, ``purge``, ``max-errors``, ``quiet``. PBBT can also be executed as a Distutils command:: python setup.py pbbt In this case, PBBT configuration could be specified in ``setup.cfg`` or via command-line parameters. API Reference ============= ``pbbt.maybe(T)`` Pseudo-type for ``isinstance(X, ...)``: checks if ``X`` is an instance of ``T`` or equal to ``None``. ``pbbt.oneof(T1, T2, ...)`` Pseudo-type for ``isinstance(X, ...)``: checks if ``X`` is an instance of ``T1`` or an instance of ``T2``, etc. ``pbbt.choiceof(values)`` Pseudo-type for ``isinstance(X, ...)``: checks if ``X`` is equal to one of the given values. ``pbbt.listof(T, length=None)`` Pseudo-type for ``isinstance(X, ...)``: checks if ``X`` is a list of elements of ``T``. ``pbbt.tupleof(T1, T2, ...)`` Pseudo-type for ``isinstance(X, ...)``: checks if ``X`` is a tuple with fields of types ``T1``, ``T2``, etc. ``pbbt.dictof(T1, T2)`` Pseudo-type for ``isinstance(X, ...)``: checks if ``X`` is a dictionary with keys of type ``T1`` and values of type ``T2``. ``pbbt.raises(E)`` Use with ``with`` clause to verify that the nested block raises an exception of the given type. ``pbbt.raises(E, fn, *args, **kwds)`` Verifies that the function call ``fn(*args, **kwds)`` raises an exception of the given type. ``pbbt.Test(CaseType)`` Registers the given class as a test type. ``pbbt.Field(check=None, default=REQUIRED, order=None, hint=None)`` Describes a field of an input or an output record. ``check`` The type of the field value. ``default`` Default value if the field is missing. If not set, the field is mandatory. ``order`` If set, allows you to override the default field order. ``hint`` Short description of the field. ``pbbt.Record(*p_fields, **kv_fields)`` Base class for all input and output records. The ``Test`` decorator converts nested ``Input`` and ``Output`` classes to ``Record`` subclasses. The following methods could be used or overridden: ``classmethod __recognizes__(keys)`` Checks if the set of keys is compatible with the record type. The default implementation checks if the set of keys contains all mandatory record fields. ``classmethod __load__(mapping)`` Generates a record instance from a mapping of record keys and values. ``__dump__()`` Generates a list of field keys and values. ``__complements__(other)`` Checks if two records are complementary input and output records for the same test case. ``__clone__(**kv_fields)`` Makes a copy of the record with new values for the given fields. ``__str__()`` Generates a printable representation. ``pbbt.Control(...)`` Test harness. The test harness object is passed to test cases as the first argument of the constructor. The following methods and attributes could be used by test case objects. Attributes: ``ui`` Provides user interaction services. ``training`` If set, the harness is in training mode. ``purging`` If set, the harness is in purging mode. ``quiet`` If set, only warnings and errors are displayed. ``halted`` If set, the test process has been halted. ``state`` Conditional variables. ``selection`` Selected suites. Methods: ``passed(text=None)`` Attests that the current test case has passed. ``failed(text=None)`` Attests that the current test case has failed. ``updated(text=None)`` Attests that output data for the current test case has been updated. ``halt(text=None)`` Halts testing process. ``load_input(path)`` Loads input test data from the given file. ``load_output(path)`` Loads output test data from the given file. ``dump_output(path, data)`` Saves output test data to the given file. ``run(case)`` Executes a test case. ``__call__(input_path, output_path)`` Runs testing process with the given input and output. ``pbbt.locate(record)`` Finds the location of the given record. ``pbbt.Location(filename, line)`` Position of an input or output record in the YAML document. ``pbbt.run(input_path, output_path=None, **configuration)`` Loads test data from the given files and runs the tests. Configuration: ``ui`` User interaction controller. ``variables`` Predefined conditional variables. ``targets`` Selected suites. ``training`` Set the harness into training mode. ``purging`` Purge stale output data. ``max_errors`` Maximum permitted number of failures before the harness halts. ``quiet`` Display only warnings and errors. ``pbbt.main()`` Implements the ``pbbt`` command-line utility. ``pbbt.BaseCase`` Template class suitable for most test types. Subclasses need to override the following methods: ``check()`` Runs the test case in check mode. ``train()`` Runs the test case in train mode. The default implementation simply calls ``check()``. ``pbbt.MatchCase`` Template class for test types which produce output. Subclasses need to override the following methods: ``run()`` Executes the case; returns produced output. ``render(output)`` Converts output record to text. ``pbbt.UI`` Abstract class for user interaction services. Methods: ``part()`` Starts a new section. ``section()`` Starts a subsection. ``header(text)`` Shows a section header. ``notice(text)`` Shows a notice. ``warning(text)`` Shows a warning. ``error(text)`` Shows an error. ``literal(text)`` Shows a literal text. ``choice(text, *choices)`` Asks a single-choice question. ``pbbt.ConsoleUI(stdin=None, stdout=None, stderr=None)`` Implements ``UI`` for console input/output. ``pbbt.SilentUI(backend)`` Implements ``UI`` for use with ``--quiet`` option. .. _YAML: http://yaml.org/ .. _Prometheus Research, LLC: http://prometheusresearch.com/ .. _pip: http://pip-installer.org/ .. _Python Package Index: http://pypi.python.org/pypi/pbbt .. _JSON: http://json.org/ .. vim: set spell spelllang=en textwidth=72: