add unit tests (#60)

also, flatten the workspace into a single crate. I forget what the original reason for the workspace
was -- I think it was added because `cargo t -p testsuite` is nicer than running
`cargo t --test $filename` N times. However, a single crate removes the need to repeat the list of
dependencies in `testsuite/Cargo.toml`

also, document the two sets of tests included with the template and how to run them in the README
file

Cargo.toml

@@ -5,8 +5,13 @@ name = "{{project-name}}"
 edition = "2018"
 version = "0.1.0"
 
-[workspace]
-members = ["testsuite"]
+[lib]
+harness = false
+
+# needed for each integration test
+[[test]]
+name = "integration"
+harness = false
 
 [dependencies]
 cortex-m = "0.7.3"
@@ -17,6 +22,9 @@ panic-probe = { version = "0.3.0", features = ["print-defmt"] }
 # TODO(4) enter your HAL here
 # some-hal = "1.2.3"
 
+[dev-dependencies]
+defmt-test = "0.3.0"
+
 # cargo build/run
 [profile.dev]
 codegen-units = 1

README.md

@@ -139,7 +139,7 @@ $ echo $?
 ```
 
 If you're running out of memory (`flip-link` bails with an overflow error), you can decrease the size of the device memory buffer by setting the `DEFMT_RTT_BUFFER_SIZE` environment variable. The default value is 1024 bytes, and powers of two should be used for optimal performance:
- 
+
 ``` console
 $ DEFMT_RTT_BUFFER_SIZE=64 cargo rb hello
 ```
@@ -154,12 +154,41 @@ If you are using [rust-analyzer] with VS Code for IDE-like features you can add
         "Cargo.toml",
         "firmware/Cargo.toml",
     ]
-} 
+}
 ```
 
 [RA docs]: https://rust-analyzer.github.io/manual.html#configuration
 [rust-analyzer]: https://rust-analyzer.github.io/
 
+## Running tests
+
+The template comes configured for running unit tests and integration tests on the target.
+
+Unit tests reside in the library crate and can test private API; the initial set of unit tests are in `src/lib.rs`.
+`cargo test --lib` will run those unit tests.
+
+``` console
+$ cargo test --lib
+(1/1) running `it_works`...
+└─ app::unit_tests::__defmt_test_entry @ src/lib.rs:33
+all tests passed!
+└─ app::unit_tests::__defmt_test_entry @ src/lib.rs:28
+```
+
+Integration tests reside in the `tests` directory; the initial set of integration tests are in `tests/integration.rs`.
+`cargo test --test integration` will run those integration tests.
+Note that the argument of the `--test` flag must match the name of the test file in the `tests` directory.
+
+``` console
+$ cargo test --test integration
+(1/1) running `it_works`...
+└─ integration::tests::__defmt_test_entry @ tests/integration.rs:13
+all tests passed!
+└─ integration::tests::__defmt_test_entry @ tests/integration.rs:8
+```
+
+Note that to add a new test file to the `tests` directory you also need to add a new `[[test]]` section to `Cargo.toml`.
+
 ## Trying out the git version of defmt
 
 This template is configured to use the latest crates.io release (the "stable" release) of the `defmt` framework.

src/lib.rs

@@ -1,3 +1,4 @@
+#![no_main]
 #![no_std]
 
 use defmt_rtt as _; // global logger
@@ -20,3 +21,17 @@ pub fn exit() -> ! {
         cortex_m::asm::bkpt();
     }
 }
+
+// defmt-test 0.3.0 has the limitation that this `#[tests]` attribute can only be used
+// once within a crate. the module can be in any file but there can only be at most
+// one `#[tests]` module in this library crate
+#[cfg(test)]
+#[defmt_test::tests]
+mod unit_tests {
+    use defmt::assert;
+
+    #[test]
+    fn it_works() {
+        assert!(true)
+    }
+}

tests/integration.rs

@@ -0,0 +1,16 @@
+#![no_std]
+#![no_main]
+
+use {{crate_name}} as _; // memory layout + panic handler
+
+// See https://crates.io/crates/defmt-test/0.3.0 for more documentation (e.g. about the 'state'
+// feature)
+#[defmt_test::tests]
+mod tests {
+    use defmt::assert;
+
+    #[test]
+    fn it_works() {
+        assert!(true)
+    }
+}