* Test coverage improvements
Implements #397 and #591, might help with #473
Test coverage for core is 97.6% with only real fringe cases remaining.
Improve `Fields` `isNilValue()` portability.
Added a new global handler `FatalExitFunc` to allow intercepting `Fatal()` messages.
Fixed CBOR float constants (removed the CBOR prefix)
Added tests for:
- global `FatalExitFunc` to allow intercepting Fatal messages (both for testing and public use).
- `Logger`
- `DisableSampling`
- `.With()` copying existing context if present.
- `.With().Fields()` all forms of `ErrorStackMarshaler` returns.
- `.WithLevel()` for `FatalLevel`, `PanicLevel`, and `DisabledLevel`.
- `.Err()` with `nil` and non-`nil` `error` and test the resulting log level.
- `.should()` covering `nil` writer.
- `.Output()` gets context values.
- `.UpdateContext()` on a disabled logger doesn't panic and is a nop.
- `.With()` all forms of `ErrorStackMarshaler` returns.
- with a `nil`writer.
- `.Hook()` passing no hooks.
- `Array`
- `.MarshalZerologArray` is a nop that won't panic.
- `Context`
- ` .Err()` and `.AnErr()` for `nil` errors and all forms of `ErrorStackMarshaler` returns.
- `Event`
- `.Caller()` to ensure we don't panic or add invalid information if `runtime.Caller()` fails
-` .Err()` and `.AnErr()` for `nil` errors and all forms of `ErrorStackMarshaler` returns.
- `Fields`
- ` .appendFields()` all forms of `ErrorStackMarshaler` returns.
- `HookLevel`
- `.Run()` methods.
- `LevelSampler`
- `.Sample() methods.
- `Syslog`
- `.Write()`, `.WriteLevel()`, and `.Close()` methods.
- `.WriteLevel()` with an `InvalidLevel`.
- `Writer`
- `.Write()` short write and error cases.
- `MultiLevelWriter` `.WriteLevel()` and for `.Write()` error and `.Close()` cases.
- test of unmarshalling a level byte returns correct error.
- CBOR decodeStream
- `.decodeFloat()`, `.binaryFmt()`, `.DecodeIfBinaryToString()`, `.DecodeObjectToStr()`, `.DecodeIfBinaryToBytes()`, `.decodeTagData()`, and `.decodeSimpleFloat()`
- handling of invalid UTF-8 sequences
- handling of UTC times.
- handling of timestamps
- handling of various map lengths
Restructure `Event` `.caller()` so we test for ok and eliminate untestable coverage hole.
Restructure `Context` `.Err()` when the `ErrorStackMarshaler` returns a `nil` so there's code to cover.
Inverted logic for`Event` `.Caller()`'s call to `runtime.Caller()` for simpler testing.
Inverted logic for `Array` `.putArray()` and `Event` `.putEvent()` so there isn't uncoverable code.
Restructure `Field` `.appendFieldList()` to early return when `ErrorStackMarshaler` returns a `nil`
Added comments for things we can't get coverage on.
Did a go fmt ./...
Coverage of core is now 100% on `Array`, `Context`, `Ctx`, `Event`, `Field`, `Hook`, and `Syslog`.
Coverage of `Globals`, `Log`, `Sampler`, and `Writer` is almost all except some real edge-cases.
JSON encoder coverage is 100%
CBOR encoder coverage is 96.3% with base, cbor, string, time and types at 100% and decode_stream (which is lacks coverage on some panic states, and two incorrect coverage-tool lapses)
* Fix CBOR tests for StackMarshaler
Forgot to use the `decodeIfBinaryToString()`
Marc Brooks