diff --git a/README.md b/README.md
index 0b302ca..f0479cd 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,43 @@ You include a small bash script inside your commit messages, and `git-check-asse
 
 ⚠️ Only run this on repositories and branches that you trust, since the `bash` scripts in the commit messages can do whatever they want.
 
+## Installation
+
+On most systems, clone this repository and add the `bin` directory to your `PATH`.
+
+If you use Nix with flakes, you can simply add it to your program's devshell instead:
+
+```diff
+@@ -2,12 +2,18 @@
+   inputs = {
+     nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+     flake-utils.url = "github:numtide/flake-utils";
++    git-check-assertions = {
++      url = "git+https://codeberg.org/svenvanheugten/git-check-assertions.git?ref=main";
++      inputs.nixpkgs.follows = "nixpkgs";
++      inputs.flake-utils.follows = "flake-utils";
++    };
+   };
+   outputs =
+     {
+       self,
+       nixpkgs,
+       flake-utils,
++      git-check-assertions,
+     }:
+     flake-utils.lib.eachDefaultSystem (
+       system:
+@@ -17,7 +23,10 @@
+       {
+         packages.default = pkgs.callPackage ./default.nix { };
+         devShells.default = pkgs.mkShell {
+-          packages = [ ];
++          packages = [ git-check-assertions.packages.${system}.default ];
+         };
+       }
+     )
+```
+
 ## Examples of commit messages
 
 Assert that a commit builds:
diff --git a/git-check-assertions b/bin/git-check-assertions
similarity index 90%
rename from git-check-assertions
rename to bin/git-check-assertions
index a023370..f7fe936 100755
--- a/git-check-assertions
+++ b/bin/git-check-assertions
@@ -25,7 +25,10 @@
 set -euo pipefail
 
 assert_fails() {
-  ! "$@" || { echo "Expected command to fail, but it succeeded."; exit 1; }
+  ! "$@" || {
+    echo "Expected command to fail, but it succeeded."
+    exit 1
+  }
 }
 export -f assert_fails
 
@@ -42,9 +45,9 @@ for commit_hash in "${commits[@]}"; do
   git -c advice.detachedHead=false checkout -q "$commit_hash"
   commit_msg="$(git log -1 --format=%B "$commit_hash")"
   # shellcheck disable=SC2016
-  block="$(printf '%s\n' "$commit_msg" \
-    | sed -n '/^```git-check-assertions[[:space:]]*$/,/^```[[:space:]]*$/p' \
-    | sed '1d;$d')"
+  block="$(printf '%s\n' "$commit_msg" |
+    sed -n '/^```git-check-assertions[[:space:]]*$/,/^```[[:space:]]*$/p' |
+    sed '1d;$d')"
   if [ -n "$block" ]; then
     echo "git-check-assertions block in $commit_hash:"
     printf '%s\n' "$block" | sed 's/^/> /'
diff --git a/default.nix b/default.nix
index 4dde1cf..d8055a8 100644
--- a/default.nix
+++ b/default.nix
@@ -8,6 +8,7 @@
   shellcheck-minimal,
   gitMinimal,
   resholve,
+  shfmt,
 }:
 
 let
@@ -20,8 +21,9 @@ resholve.mkDerivation {
   src = fs.toSource {
     root = ./.;
     fileset = fs.unions [
-      ./git-check-assertions
-      ./test.bats
+      ./.editorconfig
+      ./bin
+      ./test
     ];
   };
 
@@ -31,19 +33,20 @@ resholve.mkDerivation {
 
   nativeCheckInputs = [
     shellcheck-minimal
-    bats
+    (bats.withLibraries (p: [
+      p.bats-assert
+      p.bats-support
+      p.bats-file
+    ]))
     gitMinimal
+    shfmt
   ];
 
   checkPhase = ''
     runHook preCheck
-    shellcheck git-check-assertions test.bats
-    git init
-    git config user.email test
-    git config user.name test
-    git checkout -b main
-    git commit --allow-empty -m "initial"
-    ./test.bats
+    shellcheck bin/git-check-assertions test/git-check-assertions.bats
+    shfmt -d bin/git-check-assertions test/git-check-assertions.bats
+    ./test/git-check-assertions.bats
     runHook postCheck
   '';
 
@@ -52,7 +55,7 @@ resholve.mkDerivation {
   installPhase = ''
     runHook preInstall
     mkdir -p $out/bin
-    cp $src/git-check-assertions $out/bin/git-check-assertions
+    cp $src/bin/git-check-assertions $out/bin/git-check-assertions
     runHook postInstall
   '';
 
diff --git a/flake.nix b/flake.nix
index 55f8f46..e82af69 100644
--- a/flake.nix
+++ b/flake.nix
@@ -16,7 +16,14 @@
       {
         packages.default = pkgs.callPackage ./default.nix { };
         devShells.default = pkgs.mkShell {
-          packages = with pkgs; [ bats ];
+          packages = [
+            (pkgs.bats.withLibraries (p: [
+              p.bats-assert
+              p.bats-support
+              p.bats-file
+            ]))
+            pkgs.shfmt
+          ];
         };
       }
     );
diff --git a/test.bats b/test.bats
deleted file mode 100755
index 48965fd..0000000
--- a/test.bats
+++ /dev/null
@@ -1,10 +0,0 @@
-#!/usr/bin/env bats
-
-setup() {
-  DIR="$( cd "$( dirname "$BATS_TEST_FILENAME" )" >/dev/null 2>&1 && pwd )"
-  PATH="$DIR:$PATH"
-}
-
-@test "can run" {
-  git-check-assertions
-}
diff --git a/test/git-check-assertions.bats b/test/git-check-assertions.bats
new file mode 100755
index 0000000..f58c3ea
--- /dev/null
+++ b/test/git-check-assertions.bats
@@ -0,0 +1,114 @@
+#!/usr/bin/env bats
+
+setup() {
+  set -euo pipefail
+
+  bats_load_library bats-support
+  bats_load_library bats-assert
+  bats_load_library bats-file
+
+  DIR="$(cd "$(dirname "$BATS_TEST_FILENAME")" >/dev/null 2>&1 && pwd)"
+  PATH="$DIR/../bin:$PATH"
+
+  mkdir "$BATS_TEST_TMPDIR/repo"
+  cd "$BATS_TEST_TMPDIR/repo"
+  git init -b main
+  git config user.email "john.doe@example.com"
+  git config user.name "John Doe"
+  touch readme
+  git add readme
+  git commit -m "initial"
+}
+
+commit_with_assertion() {
+  git commit --allow-empty -F - <<-EOF
+		test
+
+		\`\`\`git-check-assertions
+		$1
+		\`\`\`
+	EOF
+}
+
+@test "should not run any assertion blocks when on main" {
+  commit_with_assertion "touch ../test"
+
+  run git-check-assertions
+
+  assert_success
+  assert_file_not_exists ../test
+}
+
+@test "should not run any assertion blocks from main when on a feature branch" {
+  commit_with_assertion "touch ../test"
+  git checkout -b feature
+  git commit --allow-empty -m "feature"
+
+  run git-check-assertions
+
+  assert_success
+  assert_file_not_exists ../test
+}
+
+@test "should run all succeeding assertion blocks on the feature branch and finally return to the original branch" {
+  git checkout -b feature
+  commit_with_assertion "touch ../test1"
+  commit_with_assertion "touch ../test2"
+
+  run git-check-assertions
+
+  assert_success
+  assert_file_exists ../test1
+  assert_file_exists ../test2
+  run git symbolic-ref --short HEAD
+  assert_output "feature"
+}
+
+@test "should stop at the first failing assertion block and return to the original branch" {
+  git checkout -b feature
+  commit_with_assertion "touch ../test1 && exit 3"
+  commit_with_assertion "touch ../test2"
+
+  run git-check-assertions
+
+  assert_failure
+  assert_file_exists ../test1
+  assert_file_not_exists ../test2
+  run git symbolic-ref --short HEAD
+  assert_output "feature"
+}
+
+@test "should restore worktree when finished" {
+  git checkout -b feature
+  commit_with_assertion 'echo blah >> readme'
+
+  run git-check-assertions
+
+  assert_success
+  assert_size_zero readme
+}
+
+@test "should restore worktree between commits" {
+  git checkout -b feature
+  commit_with_assertion 'echo blah >> readme'
+  commit_with_assertion 'cp readme ../test'
+
+  run git-check-assertions
+
+  assert_success
+  assert_size_zero ../test
+}
+
+@test "assertions should run against the version of the code inside of the commit" {
+  git checkout -b feature
+  echo commit1 >readme
+  git add readme
+  commit_with_assertion 'grep commit1 readme'
+  echo commit2 >readme
+  git add readme
+  commit_with_assertion 'grep commit2 readme'
+
+  run git-check-assertions
+
+  assert_success
+}