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SimpleStorage.sol

pragma solidity ^0.4.7;
import "remix_tests.sol";
contract SimpleStorage {
  uint public storedData;

  function SimpleStorage() public {
    storedData = 100;
  }

  function set(uint x) public {
    storedData = x;
  }

  function get() public view returns (uint retVal) {
    return storedData;
  }

}

SimpleStorage_test.sol

pragma solidity ^0.4.7;
import "./SimpleStorage.sol";

contract SimpleStorageTest {
  SimpleStorage foo;
  uint i = 0;

  function beforeAll() {
    foo = new SimpleStorage();
  }

  function beforeEach() {
    if (i == 1) {
      foo.set(200);
    }
    i += 1;
  }

  function initialValueShouldBe100() public {
    Assert.equal(foo.get(), 100, "initial value is not correct");
  }

  function initialValueShouldBe200() public {
    Assert.equal(foo.get(), 200, "initial value is not correct");
  }

}