Test the parser

Write the codeMedium 2 stages

parse_line() now reads every telemetry line the ground station receives, so a mistake in it would quietly corrupt every chart and report. It deserves tests that run every time someone changes it.

Check what a good line becomes, then what the parser does with lines that aren't readings.

Write assert checks for good lines: compare the whole record parse_line() returns with the dict you expect, so every field and its type are checked. When they all hold, print:

All checks passed

For example, a line from the feed, "2026-03-14T09:30:05Z,ENG-2,412.5,C", should give {"time": "09:30:05", "sensor": "ENG-2", "value": 412.5, "unit": "C"}. Leave the function as it is.

Checks that pass

Checks that catch mistakes

Finish stage 1 to unlock this stage.

Add checks for the lines the parser must turn into None: an empty line, a line of spaces, a comment, and a line with a missing field such as "2026-03-14T09:30:10Z,TANK-1". Use is None. Then check that a good line with spaces around it still gives the right record. Keep the passed line at the end.

Checks that pass

Checks that catch mistakes

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Hints

Returning Dictionary or List

returning-dictionary-list.py

# Returning complex data structures from functions

def planet_data(name):
    """Returns dictionary with planet info."""
    database = {
        "Mars": {"diameter_km": 6779, "moons": 2, "type": "rocky"},
        "Jupiter": {"diameter_km": 139820, "moons": 95, "type": "gas giant"},
        "Saturn": {"diameter_km": 116460, "moons": 146, "type": "gas giant"}
    }
    return database.get(name, {"error": f"Planet {name} not found"})


def mission_checklist(crew_size, days):
    """Returns list of supply items scaled to crew and duration."""
    water_liters = crew_size * days * 2.5
    food_kg = crew_size * days * 1.8
    oxygen_kg = crew_size * days * 0.84

    return [
        f"Water: {water_liters:.0f} liters",
        f"Food: {food_kg:.0f} kg",
        f"Oxygen: {oxygen_kg:.1f} kg"
    ]


mars = planet_data("Mars")
print(f"Mars has {mars['moons']} moons and is {mars['type']}")

pluto = planet_data("Pluto")
print(pluto)

supplies = mission_checklist(4, 180)
print("Mission supplies needed:")
for item in supplies:
    print(f"  - {item}")

Open the full example

script.py

PythonLn 1, Col 1Spaces: 4

Loading the Python environment…

Command-line arguments (sys.argv)

Separate arguments with commas. They're passed on every Run as sys.argv[1:].