context("Expectation")
dice <- rv(1:6)
coin <- rv(c(-1, 1))
test_that("expectation correct for known cases", {
expect_equal(E(dice), 3.5)
expect_equal(E(coin), 0)
})
test_that("expectation is additive", {
expect_equal(E(dice + coin), E(dice) + E(coin))
expect_equal(E(dice + dice), 2 * E(dice))
expect_equal(E(dice + dice + dice), 3 * E(dice))
})
test_that("expectation is multiplicatve", {
expect_equal(E( 6 * dice), 6 * E(dice))
expect_equal(E( 1 * dice), 1 * E(dice))
expect_equal(E(-1 * dice), -1 * E(dice))
expect_equal(E( 0 * dice), 0 * E(dice))
})
test_that("expectation throws error if input not an rv", {
expect_error(E(5), "must be an rv object")
expect_error(E("a"), "must be an rv object")
})
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