<!-- doc/src/sgml/regress.sgml -->
<chapter id="regress">
<title>Regression Tests</title>
<indexterm zone="regress">
<primary>regression tests</primary>
</indexterm>
<indexterm zone="regress">
<primary>test</primary>
</indexterm>
<para>
The regression tests are a comprehensive set of tests for the SQL
implementation in <productname>PostgreSQL</productname>. They test
standard SQL operations as well as the extended capabilities of
<productname>PostgreSQL</productname>.
</para>
<sect1 id="regress-run">
<title>Running the Tests</title>
<para>
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 <quote>parallel</quote> and a
<quote>sequential</quote> 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.
</para>
<sect2>
<title>Running the Tests Against a Temporary Installation</title>
<para>
To run the parallel regression tests after building but before installation,
type:
<screen>
make check
</screen>
in the top-level directory. (Or you can change to
<filename>src/test/regress</filename> and run the command there.)
At the end you should see something like:
<screen>
<computeroutput>
=======================
All 193 tests passed.
=======================
</computeroutput>
</screen>
or otherwise a note about which tests failed. See <xref
linkend="regress-evaluation"/> below before assuming that a
<quote>failure</quote> represents a serious problem.
</para>
<para>
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.
</para>
<para>
If you have configured <productname>PostgreSQL</productname> to install
into a location where an older <productname>PostgreSQL</productname>
installation already exists, and you perform <literal>make check</literal>
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 <literal>configure --disable-rpath</literal>.
It is not recommended that you use this option for the final installation,
however.
</para>
<para>
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
<application>psql</application> 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 <literal>MAX_CONNECTIONS</literal> parameter. For example:
<screen>
make MAX_CONNECTIONS=10 check
</screen>
runs no more than ten tests concurrently.
</para>
</sect2>
<sect2>
<title>Running the Tests Against an Existing Installation</title>
<para>
To run the tests after installation (see <xref linkend="installation"/>),
initialize a data directory and start the
server as explained in <xref linkend="runtime"/>, then type:
<screen>
make installcheck
</screen>
or for a parallel test:
<screen>
make installcheck-parallel
</screen>
The tests will expect to contact the server at the local host and the
default port number, unless directed otherwise by <envar>PGHOST</envar> and
<envar>PGPORT</envar> environment variables. The tests will be run in a
database named <literal>regression</literal>; any existing database by this name
will be dropped.
</para>
<para>
The tests will also transiently create some cluster-wide objects, such as
roles, tablespaces, and subscriptions. These objects will have names
beginning with <literal>regress_</literal>. Beware of
using <literal>installcheck</literal> mode with an installation that has
any actual global objects named that way.
</para>
</sect2>
<sect2>
<title>Additional Test Suites</title>
<para>
The <literal>make check</literal> and <literal>make installcheck</literal> commands
run only the <quote>core</quote> regression tests, which test built-in
functionality of the <productname>PostgreSQL</productname> server. The source
distribution contains many additional test suites, most of them having
to do with add-on functionality such as optional procedural languages.
</para>
<para>
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:
<screen>
make check-world
make installcheck-world
</screen>
These commands run the tests using temporary servers or an
already-installed server, respectively, just as previously explained
for <literal>make check</literal> and <literal>make installcheck</literal>. Other
considerations are the same as previously explained for each method.
Note that <literal>make check-world</literal> builds a separate instance
(temporary data directory) for each tested module, so it requires more
time and disk space than <literal>make installcheck-world</literal>.
</para>
<para>
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
<screen>
make check-world -j8 >/dev/null
</screen>
with a <option>-j</option> limit near to or a bit more than the number
of available cores. Discarding <systemitem>stdout</systemitem>
eliminates chatter that's not interesting when you just want to verify
success. (In case of failure, the <systemitem>stderr</systemitem>
messages are usually enough to determine where to look closer.)
</para>
<para>
Alternatively, you can run individual test suites by typing
<literal>make check</literal> or <literal>make installcheck</literal> in the appropriate
subdirectory of the build tree. Keep in mind that <literal>make
installcheck</literal> assumes you've installed the relevant module(s), not
only the core server.
</para>
<para>
The additional tests that can be invoked this way include:
</para>
<itemizedlist>
<listitem>
<para>
Regression tests for optional procedural languages.
These are located under <filename>src/pl</filename>.
</para>
</listitem>
<listitem>
<para>
Regression tests for <filename>contrib</filename> modules,
located under <filename>contrib</filename>.
Not all <filename>contrib</filename> modules have tests.
</para>
</listitem>
<listitem>
<para>
Regression tests for the ECPG interface library,
located in <filename>src/interfaces/ecpg/test</filename>.
</para>
</listitem>
<listitem>
<para>
Tests for core-supported authentication methods,
located in <filename>src/test/authentication</filename>.
(See below for additional authentication-related tests.)
</para>
</listitem>
<listitem>
<para>
Tests stressing behavior of concurrent sessions,
located in <filename>src/test/isolation</filename>.
</para>
</listitem>
<listitem>
<para>
Tests for crash recovery and physical replication,
located in <filename>src/test/recovery</filename>.
</para>
</listitem>
<listitem>
<para>
Tests for logical replication,
located in <filename>src/test/subscription</filename>.
</para>
</listitem>
<listitem>
<para>
Tests of client programs, located under <filename>src/bin</filename>.
</para>
</listitem>
</itemizedlist>
<para>
When using <literal>installcheck</literal> mode, these tests will create
and destroy test databases whose names
include <literal>regression</literal>, for
example <literal>pl_regression</literal>
or <literal>contrib_regression</literal>. Beware of
using <literal>installcheck</literal> mode with an installation that has
any non-test databases named that way.
</para>
<para>
Some of these auxiliary test suites use the TAP infrastructure explained
in <xref linkend="regress-tap"/>.
The TAP-based tests are run only when PostgreSQL was configured with the
option <option>--enable-tap-tests</option>. This is recommended for
development, but can be omitted if there is no suitable Perl installation.
</para>
<para>
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
<command>make</command> or environment variable
<varname>PG_TEST_EXTRA</varname> to a whitespace-separated list, for
example:
<programlisting>
make check-world PG_TEST_EXTRA='kerberos ldap ssl'
</programlisting>
The following values are currently supported:
<variablelist>
<varlistentry>
<term><literal>kerberos</literal></term>
<listitem>
<para>
Runs the test suite under <filename>src/test/kerberos</filename>. This
requires an MIT Kerberos installation and opens TCP/IP listen sockets.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ldap</literal></term>
<listitem>
<para>
Runs the test suite under <filename>src/test/ldap</filename>. This
requires an <productname>OpenLDAP</productname> installation and opens
TCP/IP listen sockets.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ssl</literal></term>
<listitem>
<para>
Runs the test suite under <filename>src/test/ssl</filename>. This opens TCP/IP listen sockets.
</para>
</listitem>
</varlistentry>
</variablelist>
Tests for features that are not supported by the current build
configuration are not run even if they are mentioned in
<varname>PG_TEST_EXTRA</varname>.
</para>
<para>
In addition, there are tests in <filename>src/test/modules</filename>
which will be run by <literal>make check-world</literal> but not
by <literal>make installcheck-world</literal>. This is because they
install non-production extensions or have other side-effects that are
considered undesirable for a production installation. You can
use <literal>make install</literal> and <literal>make
installcheck</literal> in one of those subdirectories if you wish,
but it's not recommended to do so with a non-test server.
</para>
</sect2>
<sect2>
<title>Locale and Encoding</title>
<para>
By default, tests using a temporary installation use the
locale defined in the current environment and the corresponding
database encoding as determined by <command>initdb</command>. It
can be useful to test different locales by setting the appropriate
environment variables, for example:
<screen>
make check LANG=C
make check LC_COLLATE=en_US.utf8 LC_CTYPE=fr_CA.utf8
</screen>
For implementation reasons, setting <envar>LC_ALL</envar> does not
work for this purpose; all the other locale-related environment
variables do work.
</para>
<para>
When testing against an existing installation, the locale is
determined by the existing database cluster and cannot be set
separately for the test run.
</para>
<para>
You can also choose the database encoding explicitly by setting
the variable <envar>ENCODING</envar>, for example:
<screen>
make check LANG=C ENCODING=EUC_JP
</screen>
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.
</para>
<para>
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.
</para>
</sect2>
<sect2>
<title>Custom Server Settings</title>
<para>
Custom server settings to use when running a regression test suite can be
set in the <varname>PGOPTIONS</varname> environment variable (for settings
that allow this):
<screen>
make check PGOPTIONS="-c force_parallel_mode=regress -c work_mem=50MB"
</screen>
When running against a temporary installation, custom settings can also be
set by supplying a pre-written <filename>postgresql.conf</filename>:
<screen>
echo 'log_checkpoints = on' > test_postgresql.conf
echo 'work_mem = 50MB' >> test_postgresql.conf
make check EXTRA_REGRESS_OPTS="--temp-config=test_postgresql.conf"
</screen>
</para>
<para>
This can be useful to enable additional logging, adjust resource limits,
or enable extra run-time checks such as <xref
linkend="guc-debug-discard-caches"/>.
</para>
</sect2>
<sect2>
<title>Extra Tests</title>
<para>
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 <envar>EXTRA_TESTS</envar>. For
example, to run the <literal>numeric_big</literal> test:
<screen>
make check EXTRA_TESTS=numeric_big
</screen>
</para>
</sect2>
<sect2>
<title>Testing Hot Standby</title>
<para>
The source distribution also contains regression tests for the static
behavior of Hot Standby. These tests require a running primary server
and a running standby server that is accepting new WAL changes from the
primary (using either file-based log shipping or streaming replication).
Those servers are not automatically created for you, nor is replication
setup documented here. Please check the various sections of the
documentation devoted to the required commands and related issues.
</para>
<para>
To run the Hot Standby tests, first create a database
called <literal>regression</literal> on the primary:
<screen>
psql -h primary -c "CREATE DATABASE regression"
</screen>
Next, run the preparatory script
<filename>src/test/regress/sql/hs_primary_setup.sql</filename>
on the primary in the regression database, for example:
<screen>
psql -h primary -f src/test/regress/sql/hs_primary_setup.sql regression
</screen>
Allow these changes to propagate to the standby.
</para>
<para>
Now arrange for the default database connection to be to the standby
server under test (for example, by setting the <envar>PGHOST</envar> and
<envar>PGPORT</envar> environment variables).
Finally, run <literal>make standbycheck</literal> in the regression directory:
<screen>
cd src/test/regress
make standbycheck
</screen>
</para>
<para>
Some extreme behaviors can also be generated on the primary using the
script <filename>src/test/regress/sql/hs_primary_extremes.sql</filename>
to allow the behavior of the standby to be tested.
</para>
</sect2>
</sect1>
<sect1 id="regress-evaluation">
<title>Test Evaluation</title>
<para>
Some properly installed and fully functional
<productname>PostgreSQL</productname> installations can
<quote>fail</quote> 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
<command>diff</command> comparison against the outputs
generated on a reference system, so the results are sensitive to
small system differences. When a test is reported as
<quote>failed</quote>, 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.
</para>
<para>
The actual outputs of the regression tests are in files in the
<filename>src/test/regress/results</filename> directory. The test
script uses <command>diff</command> to compare each output
file against the reference outputs stored in the
<filename>src/test/regress/expected</filename> directory. Any
differences are saved for your inspection in
<filename>src/test/regress/regression.diffs</filename>.
(When running a test suite other than the core tests, these files
of course appear in the relevant subdirectory,
not <filename>src/test/regress</filename>.)
</para>
<para>
If you don't
like the <command>diff</command> options that are used by default, set the
environment variable <envar>PG_REGRESS_DIFF_OPTS</envar>, for
instance <literal>PG_REGRESS_DIFF_OPTS='-c'</literal>. (Or you
can run <command>diff</command> yourself, if you prefer.)
</para>
<para>
If for some reason a particular platform generates a <quote>failure</quote>
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
<xref linkend="regress-variant"/> for details.
</para>
<sect2>
<title>Error Message Differences</title>
<para>
Some of the regression tests involve intentional invalid input
values. Error messages can come from either the
<productname>PostgreSQL</productname> 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
<quote>failed</quote> regression test that can be validated by
inspection.
</para>
</sect2>
<sect2>
<title>Locale Differences</title>
<para>
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.
</para>
<para>
To run the tests in a different locale when using the
temporary-installation method, pass the appropriate
locale-related environment variables on
the <command>make</command> command line, for example:
<programlisting>
make check LANG=de_DE.utf8
</programlisting>
(The regression test driver unsets <envar>LC_ALL</envar>, 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 <literal>C</literal>) or use the following
special invocation:
<programlisting>
make check NO_LOCALE=1
</programlisting>
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 <command>initdb</command>.
</para>
<para>
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.
</para>
</sect2>
<sect2>
<title>Date and Time Differences</title>
<para>
Most of the date and time results are dependent on the time zone
environment. The reference files are generated for time zone
<literal>PST8PDT</literal> (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
<envar>PGTZ</envar> to <literal>PST8PDT</literal>, which normally
ensures proper results.
</para>
</sect2>
<sect2>
<title>Floating-Point Differences</title>
<para>
Some of the tests involve computing 64-bit floating-point numbers (<type>double
precision</type>) from table columns. Differences in
results involving mathematical functions of <type>double
precision</type> columns have been observed. The <literal>float8</literal> and
<literal>geometry</literal> 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.
</para>
<para>
Some systems display minus zero as <literal>-0</literal>, while others
just show <literal>0</literal>.
</para>
<para>
Some systems signal errors from <function>pow()</function> and
<function>exp()</function> differently from the mechanism
expected by the current <productname>PostgreSQL</productname>
code.
</para>
</sect2>
<sect2>
<title>Row Ordering Differences</title>
<para>
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 <literal>ORDER BY</literal> for every single
<literal>SELECT</literal>, 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 <literal>ORDER BY</literal> 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 <varname>work_mem</varname> or the planner cost parameters.
</para>
<para>
Therefore, if you see an ordering difference, it's not something to
worry about, unless the query does have an <literal>ORDER BY</literal> that your
result is violating. However, please report it anyway, so that we can add an
<literal>ORDER BY</literal> to that particular query to eliminate the bogus
<quote>failure</quote> in future releases.
</para>
<para>
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.
</para>
</sect2>
<sect2>
<title>Insufficient Stack Depth</title>
<para>
If the <literal>errors</literal> test results in a server crash
at the <literal>select infinite_recurse()</literal> command, it means that
the platform's limit on process stack size is smaller than the
<xref linkend="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
<varname>max_stack_depth</varname>). If you are unable to do that, an
alternative is to reduce the value of <varname>max_stack_depth</varname>.
</para>
<para>
On platforms supporting <function>getrlimit()</function>, the server should
automatically choose a safe value of <varname>max_stack_depth</varname>;
so unless you've manually overridden this setting, a failure of this
kind is a reportable bug.
</para>
</sect2>
<sect2>
<title>The <quote>random</quote> Test</title>
<para>
The <literal>random</literal> test script is intended to produce
random results. In very rare cases, this causes that regression
test to fail. Typing:
<programlisting>
diff results/random.out expected/random.out
</programlisting>
should produce only one or a few lines of differences. You need
not worry unless the random test fails repeatedly.
</para>
</sect2>
<sect2>
<title>Configuration Parameters</title>
<para>
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 <varname>enable_seqscan</varname> or
<varname>enable_indexscan</varname> could cause plan changes that would
affect the results of tests that use <command>EXPLAIN</command>.
</para>
</sect2>
</sect1>
<!-- We might want to move the following section into the developer's guide. -->
<sect1 id="regress-variant">
<title>Variant Comparison Files</title>
<para>
Since some of the tests inherently produce environment-dependent
results, we have provided ways to specify alternate <quote>expected</quote>
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.
</para>
<para>
The first mechanism allows comparison files to be selected for
specific platforms. There is a mapping file,
<filename>src/test/regress/resultmap</filename>, that defines
which comparison file to use for each platform.
To eliminate bogus test <quote>failures</quote> for a particular platform,
you first choose or make a variant result file, and then add a line to the
<filename>resultmap</filename> file.
</para>
<para>
Each line in the mapping file is of the form
<synopsis>
testname:output:platformpattern=comparisonfilename
</synopsis>
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 <literal>out</literal>. The
value corresponds to the file extension of the output file.
The platform pattern is a pattern in the style of the Unix
tool <command>expr</command> (that is, a regular expression with an implicit
<literal>^</literal> anchor at the start). It is matched against the
platform name as printed by <command>config.guess</command>.
The comparison file name is the base name of the substitute result
comparison file.
</para>
<para>
For example: some systems lack a working <literal>strtof</literal> function,
for which our workaround causes rounding errors in the
<filename>float4</filename> regression test.
Therefore, we provide a variant comparison file,
<filename>float4-misrounded-input.out</filename>, which includes
the results to be expected on these systems. To silence the bogus
<quote>failure</quote> message on <systemitem>HP-UX 10</systemitem>
platforms, <filename>resultmap</filename> includes:
<programlisting>
float4:out:hppa.*-hp-hpux10.*=float4-misrounded-input.out
</programlisting>
which will trigger on any machine where the output of
<command>config.guess</command> matches <literal>hppa.*-hp-hpux10.*</literal>.
Other lines in <filename>resultmap</filename> select the variant comparison
file for other platforms where it's appropriate.
</para>
<para>
The second selection mechanism for variant comparison files is
much more automatic: it simply uses the <quote>best match</quote> among
several supplied comparison files. The regression test driver
script considers both the standard comparison file for a test,
<literal><replaceable>testname</replaceable>.out</literal>, and variant files named
<literal><replaceable>testname</replaceable>_<replaceable>digit</replaceable>.out</literal>
(where the <replaceable>digit</replaceable> is any single digit
<literal>0</literal>-<literal>9</literal>). 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
<filename>resultmap</filename> includes an entry for the particular
test, then the base <replaceable>testname</replaceable> is the substitute
name given in <filename>resultmap</filename>.)
</para>
<para>
For example, for the <literal>char</literal> test, the comparison file
<filename>char.out</filename> contains results that are expected
in the <literal>C</literal> and <literal>POSIX</literal> locales, while
the file <filename>char_1.out</filename> contains results sorted as
they appear in many other locales.
</para>
<para>
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 <quote>correct</quote> 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.
</para>
</sect1>
<sect1 id="regress-tap">
<title>TAP Tests</title>
<para>
Various tests, particularly the client program tests
under <filename>src/bin</filename>, use the Perl TAP tools and are run
using the Perl testing program <command>prove</command>. You can pass
command-line options to <command>prove</command> by setting
the <command>make</command> variable <varname>PROVE_FLAGS</varname>, for example:
<programlisting>
make -C src/bin check PROVE_FLAGS='--timer'
</programlisting>
See the manual page of <command>prove</command> for more information.
</para>
<para>
The <command>make</command> variable <varname>PROVE_TESTS</varname>
can be used to define a whitespace-separated list of paths relative
to the <filename>Makefile</filename> invoking <command>prove</command>
to run the specified subset of tests instead of the default
<filename>t/*.pl</filename>. For example:
<programlisting>
make check PROVE_TESTS='t/001_test1.pl t/003_test3.pl'
</programlisting>
</para>
<para>
The TAP tests require the Perl module <literal>IPC::Run</literal>.
This module is available from CPAN or an operating system package.
They also require <productname>PostgreSQL</productname> to be
configured with the option <option>--enable-tap-tests</option>.
</para>
<para>
Generically speaking, the TAP tests will test the executables in a
previously-installed installation tree if you say <literal>make
installcheck</literal>, or will build a new local installation tree from
current sources if you say <literal>make check</literal>. 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.
</para>
<para>
It's important to realize that the TAP tests will start test server(s)
even when you say <literal>make installcheck</literal>; 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 <literal>make installcheck</literal> will produce a mix of
results from temporary servers and the already-running test server.
</para>
</sect1>
<sect1 id="regress-coverage">
<title>Test Coverage Examination</title>
<para>
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 <command>gcov</command>
and <command>lcov</command> programs.
</para>
<para>
A typical workflow looks like this:
<screen>
./configure --enable-coverage ... OTHER OPTIONS ...
make
make check # or other test suite
make coverage-html
</screen>
Then point your HTML browser
to <filename>coverage/index.html</filename>.
</para>
<para>
If you don't have <command>lcov</command> or prefer text output over an
HTML report, you can run
<screen>
make coverage
</screen>
instead of <literal>make coverage-html</literal>, which will
produce <filename>.gcov</filename> output files for each source file
relevant to the test. (<literal>make coverage</literal> and <literal>make
coverage-html</literal> will overwrite each other's files, so mixing them
might be confusing.)
</para>
<para>
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:
<screen>
make coverage-clean
</screen>
</para>
<para>
You can run the <literal>make coverage-html</literal> or <literal>make
coverage</literal> command in a subdirectory if you want a coverage
report for only a portion of the code tree.
</para>
<para>
Use <literal>make distclean</literal> to clean up when done.
</para>
</sect1>
</chapter>