KS Test Error Handling

[npatki]

Problem Description

As a user, I want only the relevant errors surfaced to me and expected behavior to be suppressed.

For now, focus on the KS Test metric (see #129 and #130 for more details)

Expected behavior

• Create a new MetricComputationError to be used when there is a mathematical error when computing the metric (eg. when calling scipy or dividing by zero)

For tabular and relational tests compute method:

• If there are 0 columns with valid data types, return None and throw a warning. This is not an error; the metric is simply undefined.

>>> InvertedKSTest.compute(real_data, synthetic_data, metadata)
Warning: Incompatible data types. The InvertedKSTest is only defined for column types ['datetime', 'numerical']. None were found in the data.
None

• If the entire test is resulting in mathematical errors (eg all results are invalid), throw a MetricComputationError

>>> InvertedKSTest.compute(real_data, synthetic_data, metadata)
MetricComputationError: <message>

• However, if only certain columns are returning a MetricComputationError, show a warning but keep going with the other columns

>>> InvertedKSTest.compute(real_data, synthetic_data, metadata)
Warning: InvertedKSTest returned a MetricComputationError for column 'user_age'. Skipping this column.
Warning: InvertedKSTest returned a MetricComputationError for column 'weight'. Skipping this column.
0.699382