Regression Tests {#regress}
================

regression tests

test

The regression tests are a comprehensive set of tests for the SQL
implementation in PostgreSQL. They test standard SQL operations as well
as the extended capabilities of PostgreSQL.

Running the Tests {#regress-run}
=================

The regression tests can be run against an already installed and running
server, or using a temporary installation within the build tree.
Furthermore, there is a "parallel" and a "sequential" mode for running
the tests. The sequential method runs each test script alone, while the
parallel method starts up multiple server processes to run groups of
tests in parallel. Parallel testing adds confidence that interprocess
communication and locking are working correctly.

Running the Tests Against a Temporary Installation
--------------------------------------------------

To run the parallel regression tests after building but before
installation, type:

    make check

in the top-level directory. (Or you can change to `src/test/regress` and
run the command there.) At the end you should see something like:


    =======================
     All 193 tests passed.
    =======================

or otherwise a note about which tests failed. See [Test
Evaluation](#regress-evaluation) below before assuming that a "failure"
represents a serious problem.

Because this test method runs a temporary server, it will not work if
you did the build as the root user, since the server will not start as
root. Recommended procedure is not to do the build as root, or else to
perform testing after completing the installation.

If you have configured PostgreSQL to install into a location where an
older PostgreSQL installation already exists, and you perform
`make check` before installing the new version, you might find that the
tests fail because the new programs try to use the already-installed
shared libraries. (Typical symptoms are complaints about undefined
symbols.) If you wish to run the tests before overwriting the old
installation, you\'ll need to build with `configure --disable-rpath`. It
is not recommended that you use this option for the final installation,
however.

The parallel regression test starts quite a few processes under your
user ID. Presently, the maximum concurrency is twenty parallel test
scripts, which means forty processes: there\'s a server process and a
psql process for each test script. So if your system enforces a per-user
limit on the number of processes, make sure this limit is at least fifty
or so, else you might get random-seeming failures in the parallel test.
If you are not in a position to raise the limit, you can cut down the
degree of parallelism by setting the `MAX_CONNECTIONS` parameter. For
example:

    make MAX_CONNECTIONS=10 check

runs no more than ten tests concurrently.

Running the Tests Against an Existing Installation
--------------------------------------------------

To run the tests after installation (see [???](#installation)),
initialize a data directory and start the server as explained in
[???](#runtime), then type:

    make installcheck

or for a parallel test:

    make installcheck-parallel

The tests will expect to contact the server at the local host and the
default port number, unless directed otherwise by PGHOST and PGPORT
environment variables. The tests will be run in a database named
`regression`; any existing database by this name will be dropped.

The tests will also transiently create some cluster-wide objects, such
as roles, tablespaces, and subscriptions. These objects will have names
beginning with `regress_`. Beware of using `installcheck` mode with an
installation that has any actual global objects named that way.

Additional Test Suites
----------------------

The `make check` and `make installcheck` commands run only the "core"
regression tests, which test built-in functionality of the PostgreSQL
server. The source distribution contains many additional test suites,
most of them having to do with add-on functionality such as optional
procedural languages.

To run all test suites applicable to the modules that have been selected
to be built, including the core tests, type one of these commands at the
top of the build tree:

    make check-world
    make installcheck-world

These commands run the tests using temporary servers or an
already-installed server, respectively, just as previously explained for
`make check` and `make installcheck`. Other considerations are the same
as previously explained for each method. Note that `make check-world`
builds a separate instance (temporary data directory) for each tested
module, so it requires more time and disk space than
`make installcheck-world`.

On a modern machine with multiple CPU cores and no tight
operating-system limits, you can make things go substantially faster
with parallelism. The recipe that most PostgreSQL developers actually
use for running all tests is something like

    make check-world -j8 >/dev/null

with a `-j` limit near to or a bit more than the number of available
cores. Discarding stdout eliminates chatter that\'s not interesting when
you just want to verify success. (In case of failure, the stderr
messages are usually enough to determine where to look closer.)

Alternatively, you can run individual test suites by typing `make check`
or `make installcheck` in the appropriate subdirectory of the build
tree. Keep in mind that `make
   installcheck` assumes you\'ve installed the relevant module(s), not
only the core server.

The additional tests that can be invoked this way include:

-   Regression tests for optional procedural languages. These are
    located under `src/pl`.

-   Regression tests for `contrib` modules, located under `contrib`. Not
    all `contrib` modules have tests.

-   Regression tests for the ECPG interface library, located in
    `src/interfaces/ecpg/test`.

-   Tests for core-supported authentication methods, located in
    `src/test/authentication`. (See below for additional
    authentication-related tests.)

-   Tests stressing behavior of concurrent sessions, located in
    `src/test/isolation`.

-   Tests for crash recovery and physical replication, located in
    `src/test/recovery`.

-   Tests for logical replication, located in `src/test/subscription`.

-   Tests of client programs, located under `src/bin`.

When using `installcheck` mode, these tests will create and destroy test
databases whose names include `regression`, for example `pl_regression`
or `contrib_regression`. Beware of using `installcheck` mode with an
installation that has any non-test databases named that way.

Some of these auxiliary test suites use the TAP infrastructure explained
in [TAP Tests](#regress-tap). The TAP-based tests are run only when
PostgreSQL was configured with the option `--enable-tap-tests`. This is
recommended for development, but can be omitted if there is no suitable
Perl installation.

Some test suites are not run by default, either because they are not
secure to run on a multiuser system or because they require special
software. You can decide which test suites to run additionally by
setting the `make` or environment variable `PG_TEST_EXTRA` to a
whitespace-separated list, for example:

    make check-world PG_TEST_EXTRA='kerberos ldap ssl'

The following values are currently supported:

`kerberos`

:   Runs the test suite under `src/test/kerberos`. This requires an MIT
    Kerberos installation and opens TCP/IP listen sockets.

`ldap`

:   Runs the test suite under `src/test/ldap`. This requires an OpenLDAP
    installation and opens TCP/IP listen sockets.

`ssl`

:   Runs the test suite under `src/test/ssl`. This opens TCP/IP listen
    sockets.

`wal_consistency_checking`

:   Uses `wal_consistency_checking=all` while running certain tests
    under `src/test/recovery`. Not enabled by default because it is
    resource intensive.

Tests for features that are not supported by the current build
configuration are not run even if they are mentioned in `PG_TEST_EXTRA`.

In addition, there are tests in `src/test/modules` which will be run by
`make check-world` but not by `make installcheck-world`. This is because
they install non-production extensions or have other side-effects that
are considered undesirable for a production installation. You can use
`make install` and `make
   installcheck` in one of those subdirectories if you wish, but it\'s
not recommended to do so with a non-test server.

Locale and Encoding
-------------------

By default, tests using a temporary installation use the locale defined
in the current environment and the corresponding database encoding as
determined by `initdb`. It can be useful to test different locales by
setting the appropriate environment variables, for example:

    make check LANG=C
    make check LC_COLLATE=en_US.utf8 LC_CTYPE=fr_CA.utf8

For implementation reasons, setting LC\_ALL does not work for this
purpose; all the other locale-related environment variables do work.

When testing against an existing installation, the locale is determined
by the existing database cluster and cannot be set separately for the
test run.

You can also choose the database encoding explicitly by setting the
variable ENCODING, for example:

    make check LANG=C ENCODING=EUC_JP

Setting the database encoding this way typically only makes sense if the
locale is C; otherwise the encoding is chosen automatically from the
locale, and specifying an encoding that does not match the locale will
result in an error.

The database encoding can be set for tests against either a temporary or
an existing installation, though in the latter case it must be
compatible with the installation\'s locale.

Custom Server Settings
----------------------

Custom server settings to use when running a regression test suite can
be set in the `PGOPTIONS` environment variable (for settings that allow
this):

    make check PGOPTIONS="-c force_parallel_mode=regress -c work_mem=50MB"

When running against a temporary installation, custom settings can also
be set by supplying a pre-written `postgresql.conf`:

    echo 'log_checkpoints = on' > test_postgresql.conf
    echo 'work_mem = 50MB' >> test_postgresql.conf
    make check EXTRA_REGRESS_OPTS="--temp-config=test_postgresql.conf"

This can be useful to enable additional logging, adjust resource limits,
or enable extra run-time checks such as
[???](#guc-debug-discard-caches).

Extra Tests
-----------

The core regression test suite contains a few test files that are not
run by default, because they might be platform-dependent or take a very
long time to run. You can run these or other extra test files by setting
the variable EXTRA\_TESTS. For example, to run the `numeric_big` test:

    make check EXTRA_TESTS=numeric_big

Test Evaluation {#regress-evaluation}
===============

Some properly installed and fully functional PostgreSQL installations
can "fail" some of these regression tests due to platform-specific
artifacts such as varying floating-point representation and message
wording. The tests are currently evaluated using a simple `diff`
comparison against the outputs generated on a reference system, so the
results are sensitive to small system differences. When a test is
reported as "failed", always examine the differences between expected
and actual results; you might find that the differences are not
significant. Nonetheless, we still strive to maintain accurate reference
files across all supported platforms, so it can be expected that all
tests pass.

The actual outputs of the regression tests are in files in the
`src/test/regress/results` directory. The test script uses `diff` to
compare each output file against the reference outputs stored in the
`src/test/regress/expected` directory. Any differences are saved for
your inspection in `src/test/regress/regression.diffs`. (When running a
test suite other than the core tests, these files of course appear in
the relevant subdirectory, not `src/test/regress`.)

If you don\'t like the `diff` options that are used by default, set the
environment variable PG\_REGRESS\_DIFF\_OPTS, for instance
`PG_REGRESS_DIFF_OPTS='-c'`. (Or you can run `diff` yourself, if you
prefer.)

If for some reason a particular platform generates a "failure" for a
given test, but inspection of the output convinces you that the result
is valid, you can add a new comparison file to silence the failure
report in future test runs. See [Variant Comparison
Files](#regress-variant) for details.

Error Message Differences
-------------------------

Some of the regression tests involve intentional invalid input values.
Error messages can come from either the PostgreSQL code or from the host
platform system routines. In the latter case, the messages can vary
between platforms, but should reflect similar information. These
differences in messages will result in a "failed" regression test that
can be validated by inspection.

Locale Differences
------------------

If you run the tests against a server that was initialized with a
collation-order locale other than C, then there might be differences due
to sort order and subsequent failures. The regression test suite is set
up to handle this problem by providing alternate result files that
together are known to handle a large number of locales.

To run the tests in a different locale when using the
temporary-installation method, pass the appropriate locale-related
environment variables on the `make` command line, for example:

    make check LANG=de_DE.utf8

(The regression test driver unsets LC\_ALL, so it does not work to
choose the locale using that variable.) To use no locale, either unset
all locale-related environment variables (or set them to `C`) or use the
following special invocation:

    make check NO_LOCALE=1

When running the tests against an existing installation, the locale
setup is determined by the existing installation. To change it,
initialize the database cluster with a different locale by passing the
appropriate options to `initdb`.

In general, it is advisable to try to run the regression tests in the
locale setup that is wanted for production use, as this will exercise
the locale- and encoding-related code portions that will actually be
used in production. Depending on the operating system environment, you
might get failures, but then you will at least know what locale-specific
behaviors to expect when running real applications.

Date and Time Differences
-------------------------

Most of the date and time results are dependent on the time zone
environment. The reference files are generated for time zone `PST8PDT`
(Berkeley, California), and there will be apparent failures if the tests
are not run with that time zone setting. The regression test driver sets
environment variable PGTZ to `PST8PDT`, which normally ensures proper
results.

Floating-Point Differences
--------------------------

Some of the tests involve computing 64-bit floating-point numbers
(`double
     precision`) from table columns. Differences in results involving
mathematical functions of `double
     precision` columns have been observed. The `float8` and `geometry`
tests are particularly prone to small differences across platforms, or
even with different compiler optimization settings. Human eyeball
comparison is needed to determine the real significance of these
differences which are usually 10 places to the right of the decimal
point.

Some systems display minus zero as `-0`, while others just show `0`.

Some systems signal errors from `pow()` and `exp()` differently from the
mechanism expected by the current PostgreSQL code.

Row Ordering Differences
------------------------

You might see differences in which the same rows are output in a
different order than what appears in the expected file. In most cases
this is not, strictly speaking, a bug. Most of the regression test
scripts are not so pedantic as to use an `ORDER BY` for every single
`SELECT`, and so their result row orderings are not well-defined
according to the SQL specification. In practice, since we are looking at
the same queries being executed on the same data by the same software,
we usually get the same result ordering on all platforms, so the lack of
`ORDER BY` is not a problem. Some queries do exhibit cross-platform
ordering differences, however. When testing against an already-installed
server, ordering differences can also be caused by non-C locale settings
or non-default parameter settings, such as custom values of `work_mem`
or the planner cost parameters.

Therefore, if you see an ordering difference, it\'s not something to
worry about, unless the query does have an `ORDER BY` that your result
is violating. However, please report it anyway, so that we can add an
`ORDER BY` to that particular query to eliminate the bogus "failure" in
future releases.

You might wonder why we don\'t order all the regression test queries
explicitly to get rid of this issue once and for all. The reason is that
that would make the regression tests less useful, not more, since
they\'d tend to exercise query plan types that produce ordered results
to the exclusion of those that don\'t.

Insufficient Stack Depth
------------------------

If the `errors` test results in a server crash at the
`select infinite_recurse()` command, it means that the platform\'s limit
on process stack size is smaller than the [???](#guc-max-stack-depth)
parameter indicates. This can be fixed by running the server under a
higher stack size limit (4MB is recommended with the default value of
`max_stack_depth`). If you are unable to do that, an alternative is to
reduce the value of `max_stack_depth`.

On platforms supporting `getrlimit()`, the server should automatically
choose a safe value of `max_stack_depth`; so unless you\'ve manually
overridden this setting, a failure of this kind is a reportable bug.

The "random" Test
-----------------

The `random` test script is intended to produce random results. In very
rare cases, this causes that regression test to fail. Typing:

    diff results/random.out expected/random.out

should produce only one or a few lines of differences. You need not
worry unless the random test fails repeatedly.

Configuration Parameters
------------------------

When running the tests against an existing installation, some
non-default parameter settings could cause the tests to fail. For
example, changing parameters such as `enable_seqscan` or
`enable_indexscan` could cause plan changes that would affect the
results of tests that use `EXPLAIN`.

Variant Comparison Files {#regress-variant}
========================

Since some of the tests inherently produce environment-dependent
results, we have provided ways to specify alternate "expected" result
files. Each regression test can have several comparison files showing
possible results on different platforms. There are two independent
mechanisms for determining which comparison file is used for each test.

The first mechanism allows comparison files to be selected for specific
platforms. There is a mapping file, `src/test/regress/resultmap`, that
defines which comparison file to use for each platform. To eliminate
bogus test "failures" for a particular platform, you first choose or
make a variant result file, and then add a line to the `resultmap` file.

Each line in the mapping file is of the form
testname:output:platformpattern=comparisonfilename The test name is just
the name of the particular regression test module. The output value
indicates which output file to check. For the standard regression tests,
this is always `out`. The value corresponds to the file extension of the
output file. The platform pattern is a pattern in the style of the Unix
tool `expr` (that is, a regular expression with an implicit `^` anchor
at the start). It is matched against the platform name as printed by
`config.guess`. The comparison file name is the base name of the
substitute result comparison file.

For example: some systems lack a working `strtof` function, for which
our workaround causes rounding errors in the `float4` regression test.
Therefore, we provide a variant comparison file,
`float4-misrounded-input.out`, which includes the results to be expected
on these systems. To silence the bogus "failure" message on HP-UX 10
platforms, `resultmap` includes:

    float4:out:hppa.*-hp-hpux10.*=float4-misrounded-input.out

which will trigger on any machine where the output of `config.guess`
matches `hppa.*-hp-hpux10.*`. Other lines in `resultmap` select the
variant comparison file for other platforms where it\'s appropriate.

The second selection mechanism for variant comparison files is much more
automatic: it simply uses the "best match" among several supplied
comparison files. The regression test driver script considers both the
standard comparison file for a test, `testname.out`, and variant files
named `testname_digit.out` (where the digit is any single digit
`0`-`9`). If any such file is an exact match, the test is considered to
pass; otherwise, the one that generates the shortest diff is used to
create the failure report. (If `resultmap` includes an entry for the
particular test, then the base testname is the substitute name given in
`resultmap`.)

For example, for the `char` test, the comparison file `char.out`
contains results that are expected in the `C` and `POSIX` locales, while
the file `char_1.out` contains results sorted as they appear in many
other locales.

The best-match mechanism was devised to cope with locale-dependent
results, but it can be used in any situation where the test results
cannot be predicted easily from the platform name alone. A limitation of
this mechanism is that the test driver cannot tell which variant is
actually "correct" for the current environment; it will just pick the
variant that seems to work best. Therefore it is safest to use this
mechanism only for variant results that you are willing to consider
equally valid in all contexts.

TAP Tests {#regress-tap}
=========

Various tests, particularly the client program tests under `src/bin`,
use the Perl TAP tools and are run using the Perl testing program
`prove`. You can pass command-line options to `prove` by setting the
`make` variable `PROVE_FLAGS`, for example:

    make -C src/bin check PROVE_FLAGS='--timer'

See the manual page of `prove` for more information.

The `make` variable `PROVE_TESTS` can be used to define a
whitespace-separated list of paths relative to the `Makefile` invoking
`prove` to run the specified subset of tests instead of the default
`t/*.pl`. For example:

    make check PROVE_TESTS='t/001_test1.pl t/003_test3.pl'

The TAP tests require the Perl module `IPC::Run`. This module is
available from CPAN or an operating system package. They also require
PostgreSQL to be configured with the option `--enable-tap-tests`.

Generically speaking, the TAP tests will test the executables in a
previously-installed installation tree if you say `make
    installcheck`, or will build a new local installation tree from
current sources if you say `make check`. In either case they will
initialize a local instance (data directory) and transiently run a
server in it. Some of these tests run more than one server. Thus, these
tests can be fairly resource-intensive.

It\'s important to realize that the TAP tests will start test server(s)
even when you say `make installcheck`; this is unlike the traditional
non-TAP testing infrastructure, which expects to use an already-running
test server in that case. Some PostgreSQL subdirectories contain both
traditional-style and TAP-style tests, meaning that `make installcheck`
will produce a mix of results from temporary servers and the
already-running test server.

Test Coverage Examination {#regress-coverage}
=========================

The PostgreSQL source code can be compiled with coverage testing
instrumentation, so that it becomes possible to examine which parts of
the code are covered by the regression tests or any other test suite
that is run with the code. This is currently supported when compiling
with GCC, and it requires the `gcov` and `lcov` programs.

A typical workflow looks like this:

    ./configure --enable-coverage ... OTHER OPTIONS ...
    make
    make check # or other test suite
    make coverage-html

Then point your HTML browser to `coverage/index.html`.

If you don\'t have `lcov` or prefer text output over an HTML report, you
can run

    make coverage

instead of `make coverage-html`, which will produce `.gcov` output files
for each source file relevant to the test. (`make coverage` and `make
    coverage-html` will overwrite each other\'s files, so mixing them
might be confusing.)

You can run several different tests before making the coverage report;
the execution counts will accumulate. If you want to reset the execution
counts between test runs, run:

    make coverage-clean

You can run the `make coverage-html` or `make
    coverage` command in a subdirectory if you want a coverage report
for only a portion of the code tree.

Use `make distclean` to clean up when done.
