#156: truncate text on the left by default, but make it configurable

[itamarst]

Fixes #156.

I tested the flag manually, but suggestions for additional automated tests are welcome.

[jonhoo]

This looks good to me! Could you add a small test case for this too?

[itamarst]

One of the "read this file in, get this file out" kinda tests?

[itamarst]

That is, should it be the style of test in tests/flamegraph.rs, or something else? If the latter, what would it assert?

[jonhoo]

Yup, a read-in check-out test seems great for this!

[itamarst]

So I actually have to go and regenerate all the flamegraph SVGs in the integration tests, since they no longer match checked-in output... is there a utility to do that?

[jonhoo]

Ah, because you changed the default I suppose. I don't think so, but @jasonrhansen might have something handy? An alternative is to make the test suite continue to run with cropping on the right, and then just add one test that does cropping on the left.

[jasonrhansen]

If you delete the flamegraph SVGs, the tests will recreate them for you. You could do this, then git diff and make sure the new SVGs match the originals except for the truncation.

[itamarst]

Ok, I have:

1. Updated existing tests.
2. Added a new test.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@f299685). Click here to learn what that means.
The diff coverage is 79.16%.

@@            Coverage Diff            @@
##             master     #157   +/-   ##
=========================================
  Coverage          ?   88.53%           
=========================================
  Files             ?       16           
  Lines             ?     2216           
  Branches          ?        0           
=========================================
  Hits              ?     1962           
  Misses            ?      254           
  Partials          ?        0

Impacted Files	Coverage Δ
src/collapse/perf.rs	97.39% <ø> (ø)
src/collapse/dtrace.rs	89.8% <ø> (ø)
src/flamegraph/color/mod.rs	73.04% <100%> (ø)
src/differential/mod.rs	98.38% <100%> (ø)
src/flamegraph/attrs.rs	91.91% <100%> (ø)
src/collapse/common.rs	61.11% <70.58%> (ø)

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[jonhoo]

Looks great to me, thanks!
Oh, could you please also submit a PR that updates CHANGELOG.md to point to these changes under "Unreleased"?