# `Accrue.Clock`
[🔗](https://github.com/szTheory/accrue/blob/accrue-v1.0.0/lib/accrue/clock.ex#L1)

Canonical time source for Accrue.

All code inside Accrue that needs "now" calls `Accrue.Clock.utc_now/0`
instead of `DateTime.utc_now/0`. In the test environment (`:accrue, :env`
set to `:test`) this delegates to `Accrue.Processor.Fake.now/0`, which is
backed by the Fake processor's in-memory test clock. In any other
environment it delegates to the BEAM's `DateTime.utc_now/0`.

This indirection is the mechanism that makes time-sensitive billing logic
testable without sleeping or monkeypatching. Trial expiry, dunning grace
windows, and expiring-card notices can all be exercised deterministically
by advancing `Accrue.Test.Clock` in your tests rather than waiting for
wall-clock time to pass.

## Why application env, not compile env

The `:env` flag is read at runtime via `Application.get_env/3` so host
apps can flip it in tests without recompiling Accrue. Production never
reaches the Fake branch because the default is `:prod` and host apps
never set `:accrue, :env` to anything but `:test`.

# `utc_now`

```elixir
@spec utc_now() :: DateTime.t()
```

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*Consult [api-reference.md](api-reference.md) for complete listing*