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v/vlib/context/value_test.v

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import context
type ValueContextKey = string
// This example demonstrates how a value can be passed to the context
// and also how to retrieve it if it exists.
fn test_with_value() {
f := fn (ctx context.Context, key ValueContextKey) string {
if value := ctx.value(key) {
if !isnil(value) {
return *(&string(value))
}
}
return 'key not found'
}
key := ValueContextKey('language')
value := 'VAL'
ctx := context.with_value(context.background(), key, &value)
assert value == f(ctx, key)
assert 'key not found' == f(ctx, ValueContextKey('color'))
}