Which constitutional issue was tested by president abraham lincoln's suspension of habeas corpus and the supreme court case korematsu v. united states (1944) ?

Rights of the individual versus safety of the state.

Each case tested whether or not the President can strip away an individual's rights during war in the name of safety. Lincoln wanted the right to arrest those supporting the Confederacy and posing a threat to the unity of the North. FDR interned the Japanese to protect the US from internal spies.