use cargo-llvm-cov to test and report coverage

I've been meaning to do this for a while.

Author: CobaltCause

engage.toml

@@ -86,4 +86,11 @@ script = "cargo clippy --workspace --all-targets --color=always -- -D warnings"
 [[task]]
 name = "cargo"
 group = "tests"
-script = "cargo test --workspace --all-targets --color=always -- --color=always"
+script = """
+cargo llvm-cov \
+    --workspace \
+    --all-targets \
+    --color=always \
+    -- \
+    --color=always
+"""

flake.gen.nix

@@ -42,6 +42,7 @@
       devToolchain = mkToolchain (with toolchain; [
         cargo
         clippy
+        llvm-tools
         rust-src
         rustc
 
@@ -70,6 +71,7 @@
         packages = [
           devToolchain
         ] ++ (with pkgs; [
+          cargo-llvm-cov
           engage
           nixpkgs-fmt
         ]) ++ (with pkgs.nodePackages; [