:dumptests doesn't print one test case per line

[brianhuffman]

The REPL documentation for :? :dumptests suggests that "each line" of the resulting file should contain the inputs and expected output for one random test. However, since version 2.12.0, values of larger types (arrays or records) are pretty-printed with lots of extra line breaks, so each test case covers many lines. For example:

Cryptol> :set tests=3
Cryptol> :dumptests foo.txt \(xs:[4][32]) -> xs == xs

This produces the following 12-line file:

True    [0x63ed9cea,
0xb442e53d,
0xda7f35e6,
0xa5221c2d]
True    [0x39b0818b,
0x1d79967e,
0xed26edc2,
0x2314627f]
True    [0x407dd58e,
0x3d12445c,
0x29f39490,
0xd4086e5d]

[brianhuffman]

Bisection shows that PR #1263 is where the problem originates.

[brianhuffman]

The problem is in the definition of the renderOneLine function in Utils/PP.hs:

cryptol/src/Cryptol/Utils/PP.hs

Lines 141 to 142 in 07c689a

	renderOneLine :: Doc -> String
	renderOneLine d = PP.renderString (PP.layoutCompact (runDoc mempty d))

The layoutCompact style in prettyprinter doesn't do single-line layouts; it just skips indentation. We'll need to implement this another way.

[robdockins]

I think maybe we can implement this by writing a custom rendering function that never emits any newlines. It should be easier than changing the pretty printing library.

[brianhuffman]

It would probably be worth asking the prettyprinter devs if there is a recommended way to do one-line layouts.

[kquick]

Potentially useful example: https://hackage.haskell.org/package/silkscreen-0.0.0.4

[RyanGlScott]

Fixed in #1759.