Glossary

User glossary

Terms that are part of our public API.

explicit example

A test case from @example.

@example(42)
def f(n):
    pass

Here, 42 is an explicit example.

Explicit examples are always run, in the Phase.explicit phase. Unlike Hypothesis-generated test cases, Hypothesis does not shrink explicit examples.

failing test case

A test case which causes the test to fail, usually by causing an exception to be raised.

minimal failing test case

The failing test case which has been fully shrunk (minimized) by Hypothesis. Hypothesis reports only the minimal failing test case to the user at the end of the test.

@given(st.integers())
def f(n):
    print("called with", n)
    assert n < 10

called with 0
called with 921
called with 212
...
called with 10
...
Failing test case: f(
    n=10,
)

Here, each of 921, 212, and 10 are failing test cases. 10 is the minimal failing test case.

test case

The Hypothesis-generated input to a test function.

@given(st.integers())
def f(n):
    print("called with", n)
    assume(n >= 0)

called with 0
called with 18588
called with 672780074
called with -32616
...

Here, the first four test cases are 0, 18588, 672780074, and -32616.

“Test case” may also refer to the resulting execution of an input in a test function. Above, we might say that “the test case -32616 failed the assume()”, referring to its entire execution.

Developer glossary

Terms that are part of our developer API. The developer API is intended for advanced users, researchers, and developers building on top of Hypothesis.

choice sequence

The underlying sequence of primitive values corresponding to a test case. Conceptually, a choice sequence is the sequence of random choices made in the course of generating a value in a strategy. Each test case is represented internally as a choice sequence.

The exact representation is an implementation detail and depends on the strategy. For example, the value True from booleans() is represented by the choice sequence [True], while the value [2, 42] from st.lists(st.integers()) is represented by the choice sequence [True, 2, True, 42, False].

Currently, a choice sequence consists of booleans, integers, floats, strings, and bytes.