To be safe, your instance variable should be a copy of the parameter, so that the contents of your Matrix's array cannot be changed beyond your control.
To copy the two-dimensional array, you must instantiate a new two-dimensional array and copy the original array's contents into your new array.
The .equals(Object) method included with this lab calls your arraysAreEqual method, so that Matrix equality of two matrices depends on the contents of those matrices.
Until this method is working, the rest of the JUnit tests will not work properly.
In this lab, rows are numbered as arrays are indexed. Thus, the top row in the matrix is row 0, and the bottom row is numbered one less than the number of rows in the matrix.