Testing ENG Programs

The repository uses Rust integration tests to verify interpreter behavior.

Run the test suite

cargo test

What is tested

The supplied tests cover:

hello-world execution
printed output
arithmetic
string concatenation
booleans
comparisons
logical operators
If / Otherwise
Repeat
While
functions
lists
module loading
error cases

Add a regression test

When changing the interpreter, add a small test that demonstrates the intended behavior.

A typical output test constructs a VM with a custom printer, executes source, and compares the emitted strings.

Example source:

engling
Let x be 5.
Print x.

Expected output:

Test examples manually

A quick manual test is:

cargo run -- run examples/01_hello.eng

For a larger check, run the repository's example files individually or use the test suite.

Why tests matter

ENG's parser is deliberately template-driven. A small syntax change can affect multiple sentence forms, so regression tests help preserve existing grammar while new features are added.