As an operator, I want a rover that would move off the plateau to stay in place, so that it never leaves the grid and the mission always completes normally.
Architecture Reference: 05-building-blocks.md — MoveForward command; 01-introduction.md — FR-6; 10-quality-requirements.md — QS-3, QS-4; 02-constraints.md — DC-5
Scenario ID: NAV-STORY-002-S1
GIVEN
A rover at (0, 0, S) on plateau 5 5
WHEN
Command M is executed
THEN
Rover stays at (0, 0, S) and no exception is raised
Scenario ID: NAV-STORY-002-S2
GIVEN
A rover at (5, 5, N) on plateau 5 5
WHEN
Command M is executed
THEN
Rover stays at (5, 5, N) and no exception is raised
Scenario ID: NAV-STORY-002-S3
GIVEN
A rover at (0, 0, W) on plateau 5 5
WHEN
Command M is executed
THEN
Rover stays at (0, 0, W) and no exception is raised
Scenario ID: NAV-STORY-002-S4
GIVEN
A rover at (5, 0, E) on plateau 5 5
WHEN
Command M is executed
THEN
Rover stays at (5, 0, E) and no exception is raised
Scenario ID: NAV-STORY-002-S5
GIVEN
A rover receives MMM but only 1 step is valid
WHEN
All 3 commands execute
THEN
Rover moves 1 step, then stays in place for the remaining 2
Mission completes normally with no error
Story ID: NAV-BE-002.1
As a developer I want MoveForward to silently ignore out-of-bounds moves so that boundary violations never raise exceptions or abort the mission.
Architecture Reference: 05-building-blocks.md — MoveForward; 08-cross-cutting-concepts.md — safe-stop contract; 11-risks-and-technical-debts.md — R-1
Scenarios:
Scenario ID: NAV-BE-002.1-S1
GIVEN
MoveForward is called with a rover at a boundary edge
WHEN
The computed next position is outside Plateau.is_within()
THEN
The rover’s x and y are not updated
No exception propagates to the caller
The safe-stop behaviour is already encoded in MoveForward.__call__ (NAV-STORY-001). This story adds explicit tests to verify all four boundary edges and the multi-command continuation behaviour.
No new production code is required — this story is fully covered by tests.
Mars Rover
tests/domain/test_boundary.py¶import pytest
from mars_rover.domain.commands import MoveForward, TurnRight
from mars_rover.domain.heading import Heading
from mars_rover.domain.plateau import Plateau
from mars_rover.domain.rover import Rover
@pytest.fixture
def plateau():
return Plateau(5, 5)
def test_safe_stop_south_boundary(plateau):
rover = Rover(0, 0, Heading.S)
MoveForward(plateau)(rover)
assert rover.x == 0 and rover.y == 0
def test_safe_stop_north_boundary(plateau):
rover = Rover(5, 5, Heading.N)
MoveForward(plateau)(rover)
assert rover.x == 5 and rover.y == 5
def test_safe_stop_west_boundary(plateau):
rover = Rover(0, 0, Heading.W)
MoveForward(plateau)(rover)
assert rover.x == 0 and rover.y == 0
def test_safe_stop_east_boundary(plateau):
rover = Rover(5, 0, Heading.E)
MoveForward(plateau)(rover)
assert rover.x == 5 and rover.y == 0
def test_safe_stop_does_not_raise(plateau):
rover = Rover(0, 0, Heading.S)
try:
MoveForward(plateau)(rover)
except Exception as exc:
pytest.fail(f"MoveForward raised unexpectedly: {exc}")
def test_safe_stop_allows_subsequent_commands(plateau):
rover = Rover(0, 0, Heading.S)
move = MoveForward(plateau)
move(rover) # safe-stop: stays at (0, 0, S)
TurnRight()(rover) # now facing W
TurnRight()(rover) # now facing N
move(rover) # valid move: goes to (0, 1, N)
assert rover.x == 0 and rover.y == 1 and rover.heading == Heading.N
def test_safe_stop_multiple_blocked_moves(plateau):
rover = Rover(3, 5, Heading.N)
move = MoveForward(plateau)
for _ in range(3):
move(rover)
assert rover.x == 3 and rover.y == 5
Story ID: NAV-FE-002.1
As an operator I want to receive the rover’s last safe position when a boundary is hit so that I always get a valid result with no special error handling needed.
Architecture Reference: 03-context.md — System → Operator interface
Scenarios:
Scenario ID: NAV-FE-002.1-S1
GIVEN
A rover hits a boundary during its command sequence
WHEN
The mission completes
THEN
The operator receives the rover’s last valid position in the standard x y HEADING format
No special marker or error message is emitted (contrast with obstacle detection in NAV-STORY-003)
Story ID: NAV-INFRA-002.1
As a developer I want boundary safe-stop functionality to be containerized and testable so that boundary checking works consistently across environments.
Architecture Reference: 07-deployment.md — deployment topology; 11-risks-and-technical-debts.md — R-1; 02-constraints.md — DC-5
Scenario ID: NAV-INFRA-002.1-S1
GIVEN
The Docker container includes boundary checking logic
A rover at position (0, 0, S) attempts to move forward
WHEN
The container processes the move command
THEN
A structured log is written to stderr indicating the boundary safe-stop
Log includes rover position, heading, and attempted direction
Rover position remains unchanged in the final output
Container continues processing remaining commands
Scenario ID: NAV-INFRA-002.1-S2
GIVEN
The Docker container processes a command sequence with multiple boundary violations
Multiple rovers attempt moves outside the plateau
WHEN
The container executes all commands
THEN
Each boundary violation is logged separately to stderr
All safe-stops are handled without stopping execution
Final positions reflect only valid moves
Container completes successfully with exit code 0
Scenario ID: NAV-INFRA-002.1-S3
GIVEN
The boundary checking logic is implemented in domain code
The Dockerfile includes all domain and application layers
WHEN
docker build -t mars-rover . is executed
THEN
The build includes boundary checking code and dependencies
Plateau boundary validation is available in the container
The container can perform safe-stop operations correctly
Build completes without errors
Scenario ID: NAV-INFRA-002.1-S4
GIVEN
Test files exist for boundary checking and safe-stop functionality
The Docker container includes pytest
WHEN
docker run --rm mars-rover pytest tests/ -k "boundary" -v is executed
THEN
All 7 boundary tests run inside the container
Tests validate safe-stop behavior for various boundary conditions
pytest discovers and executes all boundary-related tests
Container exits with code 0 on test success
All 7 boundary tests pass
No exception is raised on any boundary violation
Mission continues normally after a safe-stop (NAV-STORY-002-S5)
Container logs boundary safe-stops to stderr with structured metadata
Container handles multiple boundary violations gracefully
Dockerfile builds successfully with boundary checking dependencies
Test suite runs inside container and validates boundary checking
ruff, black, and isort pass with no warnings