71 lines
1.7 KiB
Markdown
71 lines
1.7 KiB
Markdown
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Unit Tests
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==========
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We're testing our calculator using cram tests, but in some cases, it can be more comfortable to use unit tests to test internal behaviors.
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In this chapter, we're going to extract the function that deals with conversion
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to floats and put it in a test harness.
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## Install Dependencies
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Run `opam install alcotest.1.7.0`.
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## Refactor
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Let's refactor our `eval_number_op` function in `lib/cli.ml` so that it uses the `as_float` function. Move `as_float` above it so that is can be used.
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```{code-block} ocaml
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let eval_number_op f_int f_float va vb =
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match (va, vb) with
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| VInt na, VInt nb -> VInt (f_int na nb)
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| _ ->
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let fa = as_float va in
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let fb = as_float vb in
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VFloat (f_float fa fb)
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```
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## Create a Test Suite
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We're first going to move our cram tests so that they can be in `test/cram/`,
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while our unit tests will be in `test/unit/`.
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Move the contents of the folder `test` into a fresh folder `test/cram/`.
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Create a folder `test/unit/`.
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Create `test/unit/dune` with the following contents:
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```dune
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(test
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(name test_calc)
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(libraries alcotest calc))
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```
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And `test/unit/test_calc.ml`:
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```ocaml
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open Calc
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let test_as_float =
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let test ~name expression ~expected =
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( Printf.sprintf "as_float(%s)" name,
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`Quick,
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fun () ->
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let got = Cli.as_float expression in
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Alcotest.check
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(Alcotest.float Stdlib.epsilon_float)
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__LOC__ expected got )
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in
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[
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test ~name:"int" (VInt 2) ~expected:2.;
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test ~name:"float" (VFloat 3.5) ~expected:3.5;
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]
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let suite = [ ("as_float", test_as_float) ]
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let () = Alcotest.run __FILE__ suite
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```
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Now run `dune runtest`. In addition to the existing cram tests, this also runs
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unit tests.
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