Unit testing support.
Unlike most Skylib files, this exports four modules:
unittest
contains functions to declare and define unit tests for ordinary Starlark functions;analysistest
contains functions to declare and define tests for analysis phase behavior of a rule, such as a given target's providers or registered actions;loadingtest
contains functions to declare and define tests for loading phase behavior, such as macros and native.*
;asserts
contains the assertions used within tests.See https://bazel.build/extending/concepts for background about macros, rules, and the different phases of a build.
ATTRIBUTES
Name | Description | Type | Mandatory | Default |
---|---|---|---|---|
name | A unique name for this target. | Name | required | |
escape_chars_with | Dictionary of characters that need escaping in test failure message to prefix appended to escape those characters. For example, {“%”: “%”, “>”: “^”} would replace % with %% and > with ^> in the failure message before that is included in success_templ. | Dictionary: String -> String | optional | {} |
escape_other_chars_with | String to prefix every character in test failure message which is not a key in escape_chars_with before including that in success_templ. For example, "" would prefix every character in the failure message (except those in the keys of escape_chars_with) with </code>. | String | optional | "" |
failure_templ | Test script template with a single %s. That placeholder is replaced with the lines in the failure message joined with the string specified in join_with. The resulting script should print the failure message and exit with non-zero status. | String | required | |
file_ext | File extension for test script, including leading dot. | String | required | |
join_on | String used to join the lines in the failure message before including the resulting string in the script specified in failure_templ. | String | required | |
success_templ | Test script generated when the test passes. Should exit with status 0. | String | required |
Creates an analysis test rule from its implementation function.
An analysis test verifies the behavior of a “real” rule target by examining and asserting on the providers given by the real target.
Each analysis test is defined in an implementation function that must then be associated with a rule so that a target can be built. This function handles the boilerplate to create and return a test rule and captures the implementation function's name so that it can be printed in test feedback.
An example of an analysis test:
def _your_test(ctx): env = analysistest.begin(ctx) # Assert statements go here return analysistest.end(env) your_test = analysistest.make(_your_test)
Recall that names of test rules must end in _test
.
PARAMETERS
Name | Description | Default Value |
---|---|---|
impl | The implementation function of the unit test. | none |
expect_failure | If true, the analysis test will expect the target_under_test to fail. Assertions can be made on the underlying failure using asserts.expect_failure | False |
attrs | An optional dictionary to supplement the attrs passed to the unit test's rule() constructor. | {} |
fragments | An optional list of fragment names that can be used to give rules access to language-specific parts of configuration. | [] |
config_settings | A dictionary of configuration settings to change for the target under test and its dependencies. This may be used to essentially change ‘build flags’ for the target under test, and may thus be utilized to test multiple targets with different flags in a single build | {} |
extra_target_under_test_aspects | An optional list of aspects to apply to the target_under_test in addition to those set up by default for the test harness itself. | [] |
doc | A description of the rule that can be extracted by documentation generating tools. | "" |
RETURNS
A rule definition that should be stored in a global whose name ends in _test
.
Begins an analysis test.
This should be the first function called in an analysis test implementation function. It initializes a “test environment” that is used to collect assertion failures so that they can be reported and logged at the end of the test.
PARAMETERS
Name | Description | Default Value |
---|---|---|
ctx | The Starlark context. Pass the implementation function's ctx argument in verbatim. | none |
RETURNS
A test environment struct that must be passed to assertions and finally to analysistest.end
. Do not rely on internal details about the fields in this struct as it may change.
Ends an analysis test and logs the results.
This must be called and returned at the end of an analysis test implementation function so that the results are reported.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by analysistest.begin. | none |
RETURNS
A list of providers needed to automatically register the analysis test result.
Unconditionally causes the current test to fail.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
msg | The message to log describing the failure. | none |
Returns a list of actions registered by the target under test.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by analysistest.begin. | none |
RETURNS
A list of actions registered by the target under test
Returns ctx.bin_dir.path for the target under test.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by analysistest.begin. | none |
RETURNS
Output bin dir path string.
Returns the target under test.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by analysistest.begin. | none |
RETURNS
The target under test.
Asserts that the target under test has failed with a given error message.
This requires that the analysis test is created with analysistest.make()
and expect_failures = True
is specified.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by analysistest.begin. | none |
expected_failure_msg | The error message to expect as a result of analysis failures. | "" |
Asserts that the given expected
and actual
values are equal.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
expected | The expected value of some computation. | none |
actual | The actual value returned by some computation. | none |
msg | An optional message that will be printed that describes the failure. If omitted, a default will be used. | None |
Asserts that the given condition
is false.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
condition | A value that will be evaluated in a Boolean context. | none |
msg | An optional message that will be printed that describes the failure. If omitted, a default will be used. | “Expected condition to be false, but was true.” |
Asserts that the given expected
and actual
sets are equal.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
expected | The expected set resulting from some computation. | none |
actual | The actual set returned by some computation. | none |
msg | An optional message that will be printed that describes the failure. If omitted, a default will be used. | None |
Asserts that the given expected
and actual
sets are equal.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
expected | The expected set resulting from some computation. | none |
actual | The actual set returned by some computation. | none |
msg | An optional message that will be printed that describes the failure. If omitted, a default will be used. | None |
Asserts that the given condition
is true.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
condition | A value that will be evaluated in a Boolean context. | none |
msg | An optional message that will be printed that describes the failure. If omitted, a default will be used. | “Expected condition to be true, but was false.” |
Creates a loading phase test environment and test_suite.
PARAMETERS
Name | Description | Default Value |
---|---|---|
name | name of the suite of tests to create | none |
RETURNS
loading phase environment passed to other loadingtest functions
Creates a test case for asserting state at LOADING phase.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | Loading test env created from loadingtest.make | none |
test_case | Name of the test case | none |
expected | Expected value to test | none |
actual | Actual value received. | none |
RETURNS
None, creates test case
Registers the toolchains for unittest users.
Creates a unit test rule from its implementation function.
Each unit test is defined in an implementation function that must then be associated with a rule so that a target can be built. This function handles the boilerplate to create and return a test rule and captures the implementation function's name so that it can be printed in test feedback.
The optional attrs
argument can be used to define dependencies for this test, in order to form unit tests of rules.
An example of a unit test:
def _your_test(ctx): env = unittest.begin(ctx) # Assert statements go here return unittest.end(env) your_test = unittest.make(_your_test)
Recall that names of test rules must end in _test
.
PARAMETERS
Name | Description | Default Value |
---|---|---|
impl | The implementation function of the unit test. | none |
attrs | An optional dictionary to supplement the attrs passed to the unit test's rule() constructor. | {} |
doc | A description of the rule that can be extracted by documentation generating tools. | "" |
RETURNS
A rule definition that should be stored in a global whose name ends in _test
.
Defines a test_suite
target that contains multiple tests.
After defining your test rules in a .bzl
file, you need to create targets from those rules so that blaze test
can execute them. Doing this manually in a BUILD file would consist of listing each test in your load
statement and then creating each target one by one. To reduce duplication, we recommend writing a macro in your .bzl
file to instantiate all targets, and calling that macro from your BUILD file so you only have to load one symbol.
You can use this function to create the targets and wrap them in a single test_suite target. If a test rule requires no arguments, you can simply list it as an argument. If you wish to supply attributes explicitly, you can do so using partial.make()
. For instance, in your .bzl
file, you could write:
def your_test_suite(): unittest.suite( "your_test_suite", your_test, your_other_test, partial.make(yet_another_test, timeout = "short"), )
Then, in your BUILD
file, simply load the macro and invoke it to have all of the targets created:
load("//path/to/your/package:tests.bzl", "your_test_suite") your_test_suite()
If you pass N unit test rules to unittest.suite
, N + 1 targets will be created: a test_suite
target named ${name}
(where ${name}
is the name argument passed in here) and targets named ${name}_test_${i}
, where ${i}
is the index of the test in the test_rules
list, which is used to uniquely name each target.
PARAMETERS
Name | Description | Default Value |
---|---|---|
name | The name of the test_suite target, and the prefix of all the test target names. | none |
test_rules | A list of test rules defines by unittest.test. | none |
Begins a unit test.
This should be the first function called in a unit test implementation function. It initializes a “test environment” that is used to collect assertion failures so that they can be reported and logged at the end of the test.
PARAMETERS
Name | Description | Default Value |
---|---|---|
ctx | The Starlark context. Pass the implementation function's ctx argument in verbatim. | none |
RETURNS
A test environment struct that must be passed to assertions and finally to unittest.end
. Do not rely on internal details about the fields in this struct as it may change.
Ends a unit test and logs the results.
This must be called and returned at the end of a unit test implementation function so that the results are reported.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
RETURNS
A list of providers needed to automatically register the test result.
Unconditionally causes the current test to fail.
PARAMETERS
Name | Description | Default Value |
---|---|---|
env | The test environment returned by unittest.begin. | none |
msg | The message to log describing the failure. | none |