With the draft to support both gob and protobuf as serialisation formats
for Packer, along with the SDK changes that propel them, we add a series
of tests that make sure the logic that picks which protocol is solid and
functional.
These tests rely on building several versions of the tester plugin, with
and without protobuf support, to then install them in the tests as
needed to test the logic of Packer using packer build with them, and
templates that require multiple plugins.
In order for the creation of a temporary directory to install plugins
into to be simpler to understand and use, we change how the directory is
created, cleaned-up, and installs plugins into.
Now, instead of a tuple of a string (path) and a cleanup function, we
return a structure that comprises the test suite, and the temporary
directory, along with methods to handle those steps independently.
When using a PackerCommand, the Run function was made public as a way to
access the contents of an execution.
This was clumsy as it had too many responsabilities, and was not needed
strictly as Assert was performing the executions, as many times as
required.
This could introduce cases in which one run as spent by the caller, then
the remainder were executed through Assert.
Therefore, we change this convention.
Now, run is private to the type, and only through Assert can a command
be executed.
If a test needs access to a command's output, stderr, or error, it can
do so through the Output function, which requires Assert to be called
first.
When a command asserts its output with checkers, by default it will
register errors through a t.Errorf.
While this works, in some cases we would want to stop execution
immediately if a function's Assert fails, as the rest of the test may
depend on the assertion being valid.
In the current state, this means either getting the result of the run to
check if an error was returned (not fully reliable as if the command was
run multiple times, and the last run succeeded, we won't get an error),
or relying on t.IsFailed() (completely reliable).
Instead, we introduce a new function on packerCommand, that lets users
change how Assert behaves, so that if an error was reported, instead of
logging the error and flagging the test as failed, we can use t.Fatalf,
so that the test immedately fails and stops execution.
The lib name for the common components for writing packer_test suites
was not clear, and did not follow the convention established in Packer
core and plugins.
Therefore this commit does two things: first the lib is renamed into
common as to follow this convention, and clearly document which
components are common to all tests.
Also checkers are placed in a subpackage of common, common/check, so
that it is clearer what is meant to be used as checks for a command's
execution status after it's been run, as part of Assert.
The interface for building a plugin through the test suite was
confusing, as it would build the plugin and return its path, cache the
path for the version built, and return the path regardless if something
was built or not.
While in the current state this is harmless as builds are idempotent,
since the state of the plugin package/module does not change, this will
in the future as we introduce customisation techniques on the plugin's
directory and files, making this double-use potentially dangerous.
Furthermore, the current behaviour is unclear, as the function hides
that caching mechanism, which could come as a surprise for users
attempting to build a plugin for the duration of a test, while the built
plugin is linked to the test suite being run, and not the unit test
being evaluated.
Therefore this commit changes the sequence in which plugins are built
and used. Now the `CompilePlugin` function builds a plugin, and does not
return its path anymore, instead terminating the tests immediately if
they fail.
In normal test usage, a new `GetPluginPath` function is introduced,
which looks-up the path in the suite's cache, failing immediately if
invoked before the plugin is built.
With this change, it is heavily advised to build plugins when
initialising the suite, then in the tests, the GetPluginPath function
should be used to get a plugin's path for interacting with packer
commands.
Having only one test suite for the whole of Packer makes it harder to
segregate between test types, and makes for a longer runtime as no tests
run in parallel by default.
This commit splits the packer_test suite into several components in
order to make extension easier.
First we have `lib`: this package embeds the core for running Packer
test suites. This ships facilities to build your own test suite for
Packer core, and exposes convenience methods and structures for building
plugins, packer core, and use it to run a test suite in a temporary
directory.
Then we have two separate test suites: one for plugins, and one for core
itself, the latter of which does not depend on plugins being compiled at
all.
This sets the stage for more specialised test suites in the future, each
of which can run in parallel on different parts of the code.
