Struct OperatorTestHarness 

pub struct OperatorTestHarness<T: FFIOperator> { /* private fields */ }

Test harness for FFI operators

This harness provides a complete testing environment for FFI operators with:

• Mock FFI context with test-specific callbacks
• State management via TestContext
• Version tracking
• Log capture (to stderr for now)
• Full support for apply() and pull() driven through the zero-copy ABI

Implementations

impl<T: FFIOperator> OperatorTestHarness<T>

pub fn builder() -> TestHarnessBuilder<T>

Create a new test harness builder

pub fn apply(&mut self, input: Change) -> Result<Change>

Apply a flow change to the operator via the zero-copy ABI.

Marshals the input as a ChangeFFI borrow, drives the operator, and assembles an output Change from whatever the operator emitted via ctx.builder(). The result is also appended to the harness history so it can be inspected via harness[i], last_change(), or history_len().

pub fn insert(&mut self, row: Row) -> &mut Self

Chainable Insert: applies immediately, records output in history, panics on error.

Use for seeding state and/or inspecting emissions:

harness.insert(row1).insert(row2);
assert_eq!(harness[0].diffs.len(), 1);

pub fn update(&mut self, pre: Row, post: Row) -> &mut Self

Chainable Update: applies immediately, records output in history, panics on error.

pub fn remove(&mut self, row: Row) -> &mut Self

Chainable Remove: applies immediately, records output in history, panics on error.

pub fn history_len(&self) -> usize

Number of changes recorded in the history so far.

pub fn last_change(&self) -> Option<&Change>

Reference to the most recent change, or None if the history is empty.

pub fn clear_history(&mut self)

Clear the recorded history without affecting operator state.

pub fn pull(&mut self, row_numbers: &[RowNumber]) -> Result<Columns>

Pull rows by their row numbers. The operator emits its result via ctx.builder() as a single Insert-shaped diff; we read its post columns as the return value.

pub fn version(&self) -> CommitVersion

Get the current version

pub fn set_version(&mut self, version: CommitVersion)

Set the current version

pub fn state(&self) -> TestStateStore

Get access to the state store for assertions

pub fn assert_state<K>(&self, key: K, expected: Value)

where K: EncodableKey,

Assert that a state key exists with the given value

pub fn logs(&self) -> Vec<String>

Get captured log messages

pub fn clear_logs(&self)

Clear captured log messages

pub fn snapshot_state(&self) -> HashMap<EncodedKey, EncodedRow>

Take a snapshot of the current state

pub fn restore_state(&mut self, snapshot: HashMap<EncodedKey, EncodedRow>)

Restore state from a snapshot

pub fn reset(&mut self) -> Result<()>

Reset the harness to initial state

pub fn create_operator_context(&mut self) -> OperatorContext

Create an operator context for direct access

This is useful for testing components that need an OperatorContext without going through the apply() or pull() methods.

Example

let mut harness = TestHarnessBuilder::<MyOperator>::new().build()?;
let mut ctx = harness.create_operator_context();
let (row_num, is_new) = ctx.get_or_create_row_number(harness.operator(), &key)?;

pub fn operator(&self) -> &T

Get a reference to the operator

pub fn operator_mut(&mut self) -> &mut T

Get a mutable reference to the operator

pub fn node_id(&self) -> FlowNodeId

Get the node ID

Trait Implementations

impl<T: FFIOperator> Index<usize> for OperatorTestHarness<T>

Index into the harness history - harness[i] returns the i-th recorded Change.

Panics if i is out of bounds.

type Output = Change

The returned type after indexing.

fn index(&self, index: usize) -> &Self::Output

Performs the indexing (container[index]) operation.