TestEstimatorCore fails when training on EmptyDataView for the listed transforms.

[zeahmed]

TestEstimatorCore method tests the schema of estimator that of transformer. It trains estimator on EmptyDataView and get the schema. Then, it fits the estimator on actual data, and get the schema from transformer.

Ngram

It then verifies of both schema are same. However for the case of ngram transform, schema learnt from EmptyDataView is different from actually learned from data. The actual cause is size of ngram is zero in case of training on EmptyDataView which causes output vector type to be variable length. Additionally, some other meta are not filled properly in this case.

PCA Transform

Can not applied on EmptyDataView. Exception is thrown regrading empty data view.

Because of this following tests are failing right now.

WordBagWorkout
NgramWorkout
PcaWorkout

Need to think how to fix it.