% Testing the JDK

## Using "make test" (the run-test framework)

This new way of running tests is developer-centric. It assumes that you have

built a JDK locally and want to test it. Running common test targets is simple,

and more complex ad-hoc combination of tests is possible. The user interface is

forgiving, and clearly report errors it cannot resolve.

The main target `test` uses the jdk-image as the tested product. There is

also an alternate target `exploded-test` that uses the exploded image

instead. Not all tests will run successfully on the exploded image, but using

this target can greatly improve rebuild times for certain workflows.

Previously, `make test` was used invoke an old system for running test, and

`make run-test` was used for the new test framework. For backward compatibility

with scripts and muscle memory, `run-test` (and variants like

`exploded-run-test` or `run-test-tier1`) are kept as aliases. The old system

can still be accessed for some time using `cd test && make`.

Some example command-lines:

    $ make test-tier1

    $ make test-jdk_lang JTREG="JOBS=8"

    $ make test TEST=jdk_lang

    $ make test-only TEST="gtest:LogTagSet gtest:LogTagSetDescriptions" GTEST="REPEAT=-1"

    $ make test TEST="hotspot:hotspot_gc" JTREG="JOBS=1;TIMEOUT=8;VM_OPTIONS=-XshowSettings -Xlog:gc+ref=debug"

    $ make test TEST="jtreg:test/hotspot:hotspot_gc test/hotspot/jtreg/native_sanity/JniVersion.java"

    $ make test TEST="micro:java.lang.reflect" MICRO="FORK=1;WARMUP_ITER=2"

    $ make exploded-test TEST=tier2

### Configuration

To be able to run JTReg tests, `configure` needs to know where to find the

JTReg test framework. If it is not picked up automatically by configure, use

the `--with-jtreg=<path to jtreg home>` option to point to the JTReg framework.

Note that this option should point to the JTReg home, i.e. the top directory,

containing `lib/jtreg.jar` etc. (An alternative is to set the `JT_HOME`

environment variable to point to the JTReg home before running `configure`.)

To be able to run microbenchmarks, `configure` needs to know where to find

the JMH dependency. Use `--with-jmh=<path to JMH jars>` to point to a directory

containing the core JMH and transitive dependencies. The recommended dependencies 

can be retrieved by running `sh make/devkit/createJMHBundle.sh`, after which 

`--with-jmh=build/jmh/jars` should work.

## Test selection

All functionality is available using the `test` make target. In this use case,

the test or tests to be executed is controlled using the `TEST` variable. To

speed up subsequent test runs with no source code changes, `test-only` can be

used instead, which do not depend on the source and test image build.

For some common top-level tests, direct make targets have been generated. This

includes all JTReg test groups, the hotspot gtest, and custom tests (if

present). This means that `make test-tier1` is equivalent to `make test

TEST="tier1"`, but the latter is more tab-completion friendly. For more complex

test runs, the `test TEST="x"` solution needs to be used.

The test specifications given in `TEST` is parsed into fully qualified test

descriptors, which clearly and unambigously show which tests will be run. As an

example, `:tier1` will expand to `jtreg:$(TOPDIR)/test/hotspot/jtreg:tier1

jtreg:$(TOPDIR)/test/jdk:tier1 jtreg:$(TOPDIR)/test/langtools:tier1

jtreg:$(TOPDIR)/test/nashorn:tier1 jtreg:$(TOPDIR)/test/jaxp:tier1`. You can

always submit a list of fully qualified test descriptors in the `TEST` variable

if you want to shortcut the parser.

### JTReg

JTReg tests can be selected either by picking a JTReg test group, or a selection

of files or directories containing JTReg tests.

JTReg test groups can be specified either without a test root, e.g. `:tier1`

(or `tier1`, the initial colon is optional), or with, e.g. `hotspot:tier1`,

`test/jdk:jdk_util` or `$(TOPDIR)/test/hotspot/jtreg:hotspot_all`. The test

root can be specified either as an absolute path, or a path relative to the

JDK top directory, or the `test` directory. For simplicity, the hotspot

JTReg test root, which really is `hotspot/jtreg` can be abbreviated as

just `hotspot`.

When specified without a test root, all matching groups from all test roots

will be added. Otherwise, only the group from the specified test root will be

added.

Individual JTReg tests or directories containing JTReg tests can also be

specified, like `test/hotspot/jtreg/native_sanity/JniVersion.java` or

`hotspot/jtreg/native_sanity`. Just like for test root selection, you can

either specify an absolute path (which can even point to JTReg tests outside

the source tree), or a path relative to either the JDK top directory or the

`test` directory. `hotspot` can be used as an alias for `hotspot/jtreg` here as

well.

As long as the test groups or test paths can be uniquely resolved, you do not

need to enter the `jtreg:` prefix. If this is not possible, or if you want to

use a fully qualified test descriptor, add `jtreg:`, e.g.

`jtreg:test/hotspot/jtreg/native_sanity`.

### Gtest

Since the Hotspot Gtest suite is so quick, the default is to run all tests.

This is specified by just `gtest`, or as a fully qualified test descriptor

`gtest:all`.

If you want, you can single out an individual test or a group of tests, for

instance `gtest:LogDecorations` or `gtest:LogDecorations.level_test_vm`. This

can be particularly useful if you want to run a shaky test repeatedly.

For Gtest, there is a separate test suite for each JVM variant. The JVM variant

is defined by adding `/<variant>` to the test descriptor, e.g.

`gtest:Log/client`. If you specify no variant, gtest will run once for each JVM

variant present (e.g. server, client). So if you only have the server JVM

present, then `gtest:all` will be equivalent to `gtest:all/server`.

### Microbenchmarks

Which microbenchmarks to run is selected using a regular expression

following the `micro:` test descriptor, e.g., `micro:java.lang.reflect`. This

delegates the test selection to JMH, meaning package name, class name and even

benchmark method names can be used to select tests.

Using special characters like `|` in the regular expression is possible, but

needs to be escaped multiple times: `micro:ArrayCopy\\\\\|reflect`.

### Special tests

A handful of odd tests that are not covered by any other testing framework are

accessible using the `special:` test descriptor. Currently, this includes

`failure-handler` and `make`.

  * Failure handler testing is run using `special:failure-handler` or just

    `failure-handler` as test descriptor.

  * Tests for the build system, including both makefiles and related

    functionality, is run using `special:make` or just `make` as test

    descriptor. This is equivalent to `special:make:all`.

    A specific make test can be run by supplying it as argument, e.g.

    `special:make:idea`. As a special syntax, this can also be expressed as

    `make-idea`, which allows for command lines as `make test-make-idea`.

## Test results and summary

At the end of the test run, a summary of all tests run will be presented. This

will have a consistent look, regardless of what test suites were used. This is

a sample summary:

    ==============================

    Test summary

    ==============================

       TEST                                          TOTAL  PASS  FAIL ERROR

    >> jtreg:jdk/test:tier1                           1867  1865     2     0 <<

       jtreg:langtools/test:tier1                     4711  4711     0     0

       jtreg:nashorn/test:tier1                        133   133     0     0

    ==============================

    TEST FAILURE

Tests where the number of TOTAL tests does not equal the number of PASSed tests

will be considered a test failure. These are marked with the `>> ... <<` marker

for easy identification.

The classification of non-passed tests differs a bit between test suites. In

the summary, ERROR is used as a catch-all for tests that neither passed nor are

classified as failed by the framework. This might indicate test framework

error, timeout or other problems.

In case of test failures, `make test` will exit with a non-zero exit value.

All tests have their result stored in `build/$BUILD/test-results/$TEST_ID`,

where TEST_ID is a path-safe conversion from the fully qualified test

descriptor, e.g. for `jtreg:jdk/test:tier1` the TEST_ID is

`jtreg_jdk_test_tier1`. This path is also printed in the log at the end of the

test run.

Additional work data is stored in `build/$BUILD/test-support/$TEST_ID`. For

some frameworks, this directory might contain information that is useful in

determining the cause of a failed test.

## Test suite control

It is possible to control various aspects of the test suites using make control

variables.

These variables use a keyword=value approach to allow multiple values to be

set. So, for instance, `JTREG="JOBS=1;TIMEOUT=8"` will set the JTReg

concurrency level to 1 and the timeout factor to 8. This is equivalent to

setting `JTREG_JOBS=1 JTREG_TIMEOUT=8`, but using the keyword format means that

the `JTREG` variable is parsed and verified for correctness, so

`JTREG="TMIEOUT=8"` would give an error, while `JTREG_TMIEOUT=8` would just

pass unnoticed.

To separate multiple keyword=value pairs, use `;` (semicolon). Since the shell

normally eats `;`, the recommended usage is to write the assignment inside

qoutes, e.g. `JTREG="...;..."`. This will also make sure spaces are preserved,

as in `JTREG="VM_OPTIONS=-XshowSettings -Xlog:gc+ref=debug"`.

(Other ways are possible, e.g. using backslash: `JTREG=JOBS=1\;TIMEOUT=8`.

Also, as a special technique, the string `%20` will be replaced with space for

certain options, e.g. `JTREG=VM_OPTIONS=-XshowSettings%20-Xlog:gc+ref=debug`.

This can be useful if you have layers of scripts and have trouble getting

proper quoting of command line arguments through.)

As far as possible, the names of the keywords have been standardized between

test suites.

### JTReg keywords

#### JOBS

The test concurrency (`-concurrency`).

Defaults to TEST_JOBS (if set by `--with-test-jobs=`), otherwise it defaults to

JOBS, except for Hotspot, where the default is *number of CPU cores/2*, but

never more than 12.

#### TIMEOUT

The timeout factor (`-timeoutFactor`).

Defaults to 4.

#### TEST_MODE

The test mode (`-agentvm`, `-samevm` or `-othervm`).

Defaults to `-agentvm`.

#### ASSERT

Enable asserts (`-ea -esa`, or none).

Set to `true` or `false`. If true, adds `-ea -esa`. Defaults to true, except

for hotspot.

#### VERBOSE

The verbosity level (`-verbose`).

Defaults to `fail,error,summary`.

#### RETAIN

What test data to retain (`-retain`).

Defaults to `fail,error`.

#### MAX_MEM

Limit memory consumption (`-Xmx` and `-vmoption:-Xmx`, or none).

Limit memory consumption for JTReg test framework and VM under test. Set to 0

to disable the limits.

Defaults to 512m, except for hotspot, where it defaults to 0 (no limit).

#### OPTIONS

Additional options to the JTReg test framework.

Use `JTREG="OPTIONS=--help all"` to see all available JTReg options.

#### JAVA_OPTIONS

Additional Java options to JTReg (`-javaoption`).

#### VM_OPTIONS

Additional VM options to JTReg (`-vmoption`).

### Gtest keywords

#### REPEAT

The number of times to repeat the tests (`--gtest_repeat`).

Default is 1. Set to -1 to repeat indefinitely. This can be especially useful

combined with `OPTIONS=--gtest_break_on_failure` to reproduce an intermittent

problem.

#### OPTIONS

Additional options to the Gtest test framework.

Use `GTEST="OPTIONS=--help"` to see all available Gtest options.

### Microbenchmark keywords

#### FORK

Override the number of benchmark forks to spawn. Same as specifying `-f <num>`.

#### ITER

Number of measurement iterations per fork. Same as specifying `-i <num>`.

#### TIME

Amount of time to spend in each measurement iteration, in seconds. Same as

specifying `-r <num>`

#### WARMUP_ITER

Number of warmup iterations to run before the measurement phase in each fork.

Same as specifying `-wi <num>`.

#### WARMUP_TIME

Amount of time to spend in each warmup iteration. Same as specifying `-w <num>`.

#### RESULTS_FORMAT

Specify to have the test run save a log of the values. Accepts the same values

as `-rff`, i.e., `text`, `csv`, `scsv`, `json`, or `latex`.

#### VM_OPTIONS

Additional VM arguments to provide to forked off VMs. Same as `-jvmArgs <args>`

#### OPTIONS

Additional arguments to send to JMH.

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