Testing

assert

assert condition raises AssertionError when the condition is false, with an optional message. Unlike Python’s, it’s never compiled away.

def mean(xs: list[float]) -> float:
    assert len(xs) > 0, "mean of an empty list"
    return sum(xs) / len(xs)

print(mean([1, 2, 3]))
print(mean([]))

2.0

Traceback (most recent call last):
  File "main.tpn", line 6, in <module>
    print(mean([]))
  File "main.tpn", line 2, in mean
    assert len(xs) > 0, "mean of an empty list"
AssertionError: mean of an empty list

taipan test

taipan test finds test files, test_*.tpn and *_test.tpn, and runs each one’s test_* functions, as pytest does:

shapes.tpn

def area(width: float, height: float) -> float:
    return width * height

test_shapes.tpn

from shapes import area

def test_area():
    assert area(2, 3) == 6.0

def test_negative():
    assert area(-1, 2) == 0.0, "a negative side has no area"

taipan test

PASS test_shapes.tpn::test_area
FAIL test_shapes.tpn::test_negative
Traceback (most recent call last):
  File "test_shapes.tpn", line 7, in test_negative
    assert area(-1, 2) == 0.0, "a negative side has no area"
AssertionError: a negative side has no area
1 passed, 1 failed

• taipan test takes files and directories, . by default.
• Each test file is a main file: its top level runs first, then its tests, in order. Tests may be async.
• A test passes if it returns, and fails if it raises anything.
• The exit code is 0 when every test passed, and 1 when one failed, a file had an error, or there were no tests.

Test projects

In an SDK project, a test project is a .tpnproj with IsTestProject, so dotnet test runs it beside your C# tests:

<Project Sdk="TaipanLang.Sdk/0.4.0">
  <PropertyGroup>
    <IsTestProject>true</IsTestProject>
  </PropertyGroup>
  <ItemGroup>
    <ProjectReference Include="../Acme.Shapes/Acme.Shapes.tpnproj" />
  </ItemGroup>
</Project>

Its main file is a test file, and dotnet test writes the same report. See Projects.

Formatting in CI

taipan fmt --check . lists the files that aren’t formatted and exits 1 if there are any.