# scan works on an empty engine, even when given indexes.
scan
scan 3..7
---
<empty>
<empty>

# Append a few entries.
set_term 1
append
append foo
set_term 2
append bar
---
append → 1@1 None
append → 2@1 foo
append → 3@2 bar

# Full scan.
scan
---
1@1 None
2@1 foo
3@2 bar

# Start bound.
scan 2..
---
2@1 foo
3@2 bar

scan 4..
---
<empty>

scan 0..
---
1@1 None
2@1 foo
3@2 bar

# End bound.
scan "..2"
---
1@1 None

scan "..=2"
---
1@1 None
2@1 foo

scan "..7"
---
1@1 None
2@1 foo
3@2 bar

scan "..1"
---
<empty>

scan "..0"
---
<empty>

# Both bounds.
scan 1..2
---
1@1 None

scan "1..=2"
---
1@1 None
2@1 foo

scan 0..7
---
1@1 None
2@1 foo
3@2 bar

scan 1..1
---
<empty>

# Bounds panics.
!scan 1..0
---
Panic: range start is greater than range end in BTreeMap

!scan 7..3
---
Panic: range start is greater than range end in BTreeMap