- Getting Started with Mocha and Chai 3:16
- General Structure of Test Files 4:10
- Setting Up Mocha 4 questions
- Installing Mocha 1 objective
- Installing Chai 1 objective
- Test Suites and Test Specs (describe and it) 3:34
- Mocha Chai Basics 4 questions
- Writing Our First Test Suite 14:49
- Writing Our First Test Suite - Part 2 8:15
- Challenge: Expanding Our Expectations 9:57
- Answer: Expanding Our Expectations 12:05
- A Testing Test! 1 objective
- Assert Your Knowledge 5 questions
Preview
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Writing Our First Test Suite - Part 2
8:15In this video, we’ll continue writing our BDD outline for Battleship. We’ll write new test specs that correctly test when a ship is located at a given coordinate.
Our check for
ship function is looking good, but
0:00
we've only proven that
it will report a miss.
0:02
It tells us when no ship is located
at our given coordinates, but
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does it also correctly tell us when a ship
is located at or given coordinates?
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Let's write a new spec
that would prove it.
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Okay, so back inside shiptest.js,
I'll just copy my current spec for
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no ship present and
paste a new spec, right below it.
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Then I'll adjust the description and
expectation.
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So this description will say
should correctly report,
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a ship located, at the given coordinates.
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This spec test, whether
the function correctly finds a ship
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that is located at the given location.
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So we should change the argument
we passed, check for
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ship, to match the players
one ship location.
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So I'll change this to 0,0.
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Then I'll adjust the expected
result to be true.
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So now, when I run npn test in the consul,
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the test report assertion error,
expected,undefined to be true.
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Well currently the only timer
function returns something,
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is when no ship is found.
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So maybe we should add a matching
conditional to return true,
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when something is found.
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So in our check for
ship function inside ship methods.J S,
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will say if no ship is present,
Return false.
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Then we'll say else return true.
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All right, so let's run the test again.
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And cool.
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Now it works.
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But so far, we've only tested check for
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ship using a single ship
with a single location.
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So we should expand our test to be sure it
still works when a player has more than
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one ship, and when a ship is located
at more than one coordinate.
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So again, back inside ship test.js.
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I'll copy the spec at the very top and
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paste a new one at the bottom, then
revise my description and expectations.
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So I'll change this description to say
should handle ships located at more than
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one coordinate.
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This spec will test the same
behaviors we've already tested,
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but, with the ship having
multiple locations.
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So, inside locations,
I'll add a new coordinate of 0,1.
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Then I'll create new expectations for
this location, and
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adjust the expected result to be true.
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So, I'll simply copy this expectation,
and paste the new one right above it.
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And this will say expect check for
ship player at 0,1 to be true.
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Now, you normally don't want your unit
test to have more than one expectation,
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because it might be unclear to
someone reading it what the test is
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supposed to proof.
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Now, in this case, since we have
individual unit tests for positive and
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negative checks,
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I'm comfortable using both expectations
in this unit test for brevity.
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In fact, I'll also add an expectation for
the 0,0 location,
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just to make sure we can find both.
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And I'll set the expected
result to be true.
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All right so let's save our file and
run npm test in the console.
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And great that seems good so far.
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So it looks like check for ships doesn't
break when we give it a bigger ship.
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So let's try more than one ship.
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So I'll copy the bottom
spec inside ship_test,
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and paste a new spec right below it.
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And I'll change this spec's description
to should handle checking multiple ships.
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Then I’ll change the expectations.
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But first I’ll just add one ship.
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To the ship's array with new coordinates.
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So I’ll copy the first location and
paste the new one right below that.
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And change the coordinates to 1,
0 and 1, 1.
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Then right about the last expectation,
I'll add two new expectations for
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this new location.
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So I'll copy one of these and
paste it below.
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And for this I'll say expect
(checkForShip(player at 1, 0 .to be true
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and will add another one that says expect
check ForShip player at [1,1] to be true.
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All right so let's save this.
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Go over to the console and run npm test.
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So now our tests finally catch a bug.
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It looks like multiple
ships don't work correctly.
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So the test passes the first expectations,
which look at the first ship in the array.
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But the expectations aimed
at the second ship fail.
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It says assertion error.
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Expected false to be true.
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But we must have made
a mistake with our loop logic.
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Why else would everything work for
the first ship, that first loop, and
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then break during the second?
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So let's take another look at
our checkForShip function.
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And sure enough, I buried one of
the return statements too deep.
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The loop will currently check for
no matches after every ship, so that means
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that if the first ship isn't a match for
the given location, then the function
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returns false right away before getting
to loop again to the next ship.
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So it looks like we need to
reverse this logic a bit.
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We want the function to return false for
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no matches only after it has
checked every single ship.
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So that means it should return false
only after the loop has finished.
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But it should return true
immediately when it finds a match.
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So we can just switch things around
to capture this idea better.
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So we'll say if ship present return true,
and
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I'll delete this else condition.
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Then right before the closing bracket,
we'll say return false.
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All right so let's save this and
go over to the console and run npm test.
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And great,
it looks like the tests all passed now.
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And to be double sure, we can expand the
test suite a bit as a proof of concept.
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So let's add one more ship to
the ship's array with new coordinates.
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So I'll copy one of the locations and
paste the new one at the bottom.
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Then I'll change the coordinates to 2,0,
2,1.
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And I'll add two new coordinates.
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So this one will be 2,2.
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And the next will be 2,3.
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And then I'll go ahead and
add a new expectation.
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That says expect check for
ship for player at 2,3,
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to be true.
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So now if I go over to the council and
run npm test.
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It works great.
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That was a lot of work, so pat yourself
on the back for doing a great job.
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In the next video, we'll keep
adding specs to this test suite and
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expand our game of Battleship.
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