[Dustin L. Howett (DHowett)]

This is by no means comprehensive. It will be unmarked as draft when it
is more comprehensive.

This pull request adds some tests for resizing a TextBuffer and
reflowing its contents. Each test takes the form of an initial state and
a number of buffers of different sizes. The initial state is used to
seed the first TextBuffer, and the subsequent buffers are only used to
compare.

I manually reimplemented some of the DBCS logic to ensure that the
buffers contain exactly what they're supposed to. I know this is
non-ideal. After some of the CharRow changes in #8446 land, this will
need to be updated.

There's a cool bit of TAEF gore in here: the IDataSource. An IDataSource
allows us to programmatically return test cases. It's a code-only
version of its support for parameterized tests of the form Data:x = {0, 1, 2} .

The only downsides are...

1. It looks like COM (it is not using COM under the hood, just the COM
   ABI)
2. Property values must be returned as strings.

To best support rich test types, I used IDataSource to produce a lit of
array indices and nothing more. The test is run once for array member,
and it is the test's responsibility to look up the object to which that
index refers.

Works great though! Each reflow test is its own unit, and a failure in
an earlier reflow test will not tank a later one.

[Dustin L. Howett (DHowett)]

Looks like this:

StartGroup: ReflowTests::TestReflowCases#export0
TAEF: Data[index]: 0
[0.0] Test case "SBCS, cursor remains in buffer, no circling, no original wrap"
[0.1] Resizing to 5x5
[0.2] Resizing to 6x5
[0.3] Resizing to 7x5
EndGroup: ReflowTests::TestReflowCases#export0 [Passed]

StartGroup: ReflowTests::TestReflowCases#export1
TAEF: Data[index]: 1
[1.0] Test case "SBCS, cursor remains in buffer, no circling, with original wrap"
[1.1] Resizing to 5x5
[1.2] Resizing to 6x5
[1.3] Resizing to 7x5
EndGroup: ReflowTests::TestReflowCases#export1 [Passed]

StartGroup: ReflowTests::TestReflowCases#export2
TAEF: Data[index]: 2
[2.0] Test case "DBCS, cursor remains in buffer, no circling, with original wrap"
[2.1] Resizing to 5x5
[2.2] Resizing to 6x5
[2.3] Resizing to 7x5
[2.4] Resizing to 8x5
EndGroup: ReflowTests::TestReflowCases#export2 [Passed]

we can customize that name (export0) if we want.

[Dustin L. Howett (DHowett)]

There are 30 conditional branches in Reflow.

I hit 22 of them.
3 are error cases (never hit).
5 are in viewport position retention (the std::optional arguments).

22 + 3 + 5 = 30

[Dustin L. Howett (DHowett)]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Carlos Zamora (carlos-zamora)]

Should these [BUG] tags be filed and linked appropriately?

[Dustin L. Howett (DHowett)]

I'm probably not gonna file 20 new bugs for "reflow is broken", which is a well-known statement.

I should have used a less controversial word, like "[KNOWN BADNESS]"

[Carlos Zamora (carlos-zamora)]

It'd be cool if this got pulled out so that other tests could take advantage of this. Alas, that's already on your radar and probably out of scope for this PR.

[Deleted user (ghost)]

Hello Dustin L. Howett (@DHowett)!

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