Module predicate 

Predicate grammar + evaluator for if = conditions in step definitions.

Grammar

Form	Meaning
command_exists:<name>	command is on PATH
env:VAR	env var is present (any value, including empty)
env:VAR=value	env var is present and equals value
platform:linux / platform:macos / platform:windows	current OS
file_exists:<path>	path exists after ${VAR} resolution
!<predicate>	negation of any of the above
a,b,c	logical AND; whitespace around commas is allowed

Negation binds tighter than AND. An empty predicate string evaluates to Ok(true) (vacuously true). OR (||) is not supported yet — tracked as a follow-up.

Structs

DefaultPredicateEnv

Production PredicateEnv backed by the real OS.

MockPredicateEnv

Test double for PredicateEnv.

Enums

PredicateError

Everything that can go wrong while parsing or evaluating a predicate string.

Traits

PredicateEnv

Environment abstraction used by the predicate evaluator.

Functions

default_predicate_evaluator

Wrap a PredicateEnv into the closure signature expected by crate::runner::execute_steps.

eval

Evaluate a predicate string against the supplied environment.