diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 00000000..634b2004
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,3 @@
+[alias]
+t = "test --release"
+c = "tarpaulin --out html --release --lib --fail-under 100"
diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 31000a27..3447c343 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -10,13 +10,35 @@ env:
   CARGO_TERM_COLOR: always
 
 jobs:
-  build:
+  fmt:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - run: cargo fmt -- --check
 
+  clippy:
     runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - run: cargo clippy -- -D warnings      
+
+  test:
+    strategy:
+      matrix:
+        # https://docs.github.com/en/actions/using-jobs/choosing-the-runner-for-a-job#choosing-github-hosted-runners
+        os: [windows-latest, ubuntu-latest, macos-13]
+    runs-on: ${{ matrix.os }}    
+    steps:
+    - uses: actions/checkout@v3
+    - run: cargo t
 
+  coverage:
+    runs-on: macos-13
     steps:
     - uses: actions/checkout@v3
-    - name: Build
-      run: cargo build --verbose
-    - name: Run tests
-      run: cargo test --verbose
+    - run: cargo install cargo-tarpaulin
+    - run: cargo c
+    - uses: actions/upload-artifact@v3
+      with:
+        path: tarpaulin-report.html
+      if: always()
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index 6985cf1b..c4ee3822 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,4 @@ Cargo.lock
 
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
+tarpaulin-report.html
diff --git a/blockset/src/io.rs b/blockset/src/io.rs
new file mode 100644
index 00000000..6ddb84ed
--- /dev/null
+++ b/blockset/src/io.rs
@@ -0,0 +1,48 @@
+use std::io::{self, Read};
+
+trait Io {
+    type File: Read;
+    fn open(&mut self, path: &str) -> io::Result<Self::File>;
+    fn read_to_string(&mut self, path: &str) -> io::Result<String> {
+        let mut file = self.open(path)?;
+        let mut result = String::default();
+        file.read_to_string(&mut result)?;
+        Ok(result)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::{
+        collections::HashMap,
+        io::{self, Cursor},
+    };
+
+    use super::Io;
+
+    struct MockIo {
+        file_map: HashMap<String, Vec<u8>>,
+    }
+
+    impl Io for MockIo {
+        type File = Cursor<Vec<u8>>;
+
+        fn open(&mut self, path: &str) -> io::Result<Self::File> {
+            self.file_map
+                .get(path)
+                .map(|data| Cursor::new(data.clone()))
+                .ok_or_else(|| io::Error::new(io::ErrorKind::NotFound, "file not found"))
+        }
+    }
+
+    #[test]
+    fn test() {
+        let mut io = MockIo {
+            file_map: HashMap::default(),
+        };
+        io.file_map
+            .insert("test.txt".to_string(), "Hello, world!".as_bytes().to_vec());
+        let result = io.read_to_string("test.txt").unwrap();
+        assert_eq!(result, "Hello, world!");
+    }
+}
diff --git a/blockset/src/lib.rs b/blockset/src/lib.rs
index 7d12d9af..6352663e 100644
--- a/blockset/src/lib.rs
+++ b/blockset/src/lib.rs
@@ -1,14 +1 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}
+mod io;