bugs - Incorrect result while using SemanticImport for CSV file import

I might use this incorrectly. I want to use a .csv file that (as list) looks like:

{{"Group", "data 1", "data 2"}, {"a", 1, 5}, {"a", 2, 3}, {"a", 4, 5}, {"b", 8, 9}}

Now I want this as a Dataset, i.e. I try and import it with SemanticImport and would want to have as result

However, I can't get it to work with SemanticImport.

I can use the following code, but hoped SemanticImport would basically replace this:

Import["testdata.csv"];
dataDim = Dimensions@data;
a1 = Transpose@
   Table[data[[1, i]] -> data[[1 + j, i]], {i, dataDim[[2]]}, {j, 
     dataDim[[1]] - 1}];

testFullAss = Association[a1[[#]]] & /@ Range[dataDim[[1]] - 1];

Dataset[testFullAss]

Answer

Using

SemanticImport["testdata.csv"]

I get

on the exported data you provided which is the dataset you seek. But SemanticImport has been reported to have a few bugs, maybe that's why you can't get it to work. In the meantime, and in between time, you can use the much cleaner approach to obtain your dataset after using Import on your file:

data = {{"Group", "data 1", "data 2"}, {"a", 1, 5}, {"a", 2, 3}, {"a", 4,  5}, {"b", 8, 9}};

Then:

Dataset[AssociationThread[First @ data, #] & /@ Rest @ data]