exercises(resistor-color-duo): should not silently ignore additional colors

[dithpri]

https://github.com/exercism/zig/blob/main/exercises/practice/resistor-color-duo/test_resistor_color_duo.zig#L42-L47

This test expects the code to silently ignore any additional values in the input array.
This pretty much goes against the Zig way of doing things, the hidden assumption can lead to bugs.

$ zig zen

 * Communicate intent precisely.
 * Edge cases matter.
 * Favor reading code over writing code.
 * Only one obvious way to do things.
 * Runtime crashes are better than bugs.
 * Compile errors are better than runtime crashes.
[...]

The function should return an error instead of silently continuing when the passed in slice is longer than 2 elements.

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[ee7]

Thanks. I'm gradually getting around to cleaning up things like this. I agree that the current implementation isn't great.

I'm leaning towards removing that test case, and changing the function signature from

zig/exercises/practice/resistor-color-duo/resistor_color_duo.zig

Line 1 in caf868a

pub fn colorCode(colors: []const ColorBand) anyerror!isize {

to

pub fn colorCode(colors: [2]ColorBand) isize {

given that we probably have enough exercises to practice error sets and input validation. What do you think?

[dithpri]

Thanks. I'm gradually getting around to cleaning up things like this. I agree that the current implementation isn't great.

I'm leaning towards removing that test case, and changing the function signature from

zig/exercises/practice/resistor-color-duo/resistor_color_duo.zig

Line 1 in caf868a

pub fn colorCode(colors: []const ColorBand) anyerror!isize {

to

pub fn colorCode(colors: [2]ColorBand) isize {

given that we probably have enough exercises to practice error sets and input validation. What do you think?

Yes, that's actually even better!