Struct libcnb_test::TestContext

pub struct TestContext<'a> {
    pub pack_stdout: String,
    pub pack_stderr: String,
    pub config: TestConfig,
    /* private fields */
}

Context for a currently executing test.

Fields

pack_stdout: String

Standard output of pack, interpreted as an UTF-8 string.

pack_stderr: String

Standard error of pack, interpreted as an UTF-8 string.

config: TestConfig

The configuration used for this integration test.

Implementations

impl<'a> TestContext<'a>

pub fn prepare_container(&self) -> PrepareContainerContext<'_>

Prepares a new container with the image from the test.

This will not create nor run the container immediately. Use the returned PrepareContainerContext to configure the container, then call start_with_default_process on it to actually create and start the container.

Example:

use libcnb_test::{TestConfig, TestRunner};

TestRunner::default().run_test(
    TestConfig::new("heroku/builder:22", "test-fixtures/app"),
    |context| {
        context
            .prepare_container()
            .start_with_default_process(|container| {
                // ...
            });
    },
);

pub fn run_test<C: Borrow<TestConfig>, F: FnOnce(TestContext<'_>)>(
    self,
    config: C,
    f: F
)

Starts a subsequent integration test run.

This function behaves exactly like TestRunner::run_test, but it will reuse the OCI image from the previous test, causing the CNB lifecycle to restore any cached layers. It will use the same TestRunner as the previous test run.

This function allows testing of subsequent builds, including caching logic and buildpack behaviour when build environment variables change, stacks are upgraded and more.

Note that this function will consume the current context. This is because the image will be changed by the subsequent test, invalidating the context. Running a subsequent test must therefore be the last operation. You can nest subsequent runs if required.

Example

use libcnb_test::{assert_contains, TestConfig, TestRunner};

TestRunner::default().run_test(
    TestConfig::new("heroku/builder:22", "test-fixtures/app"),
    |context| {
        assert_contains!(context.pack_stdout, "---> Installing gems");

        let config = context.config.clone();
        context.run_test(config, |context| {
            assert_contains!(context.pack_stdout, "---> Using cached gems");
        });
    },
);

Trait Implementations

impl<'a> Drop for TestContext<'a>

fn drop(&mut self)

Executes the destructor for this type.