neural network - ANN why scaler is not fitted on test data?

Question

Why it is trained only on train data? Scaler fitting doesn't matter only the regression / classification split matters?

sc_X = StandardScaler()
X_trainscaled=sc_X.fit_transform(X_train)
X_testscaled=sc_X.transform(X_test)

question from:https://stackoverflow.com/questions/65908650/ann-why-scaler-is-not-fitted-on-test-data

Answer 1

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