Ruby bindings for existing FFI methods, plus eval_rule() (#188)

* Ruby binding

* use relative regorus crate in ruby instead of a published version, also cargo fmt

* remove unnecessary Cargo.toml, include the top level Cargo.lock in ruby gem

* ruby bindings continued- add eval_rule, fix _json methods, update README.md

also added rubocop-minitest and rubocop-rake, and added more test coverage

* update README.md to include Ruby bindings

Closes #191

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "bindings/python",
     "bindings/wasm",
     "bindings/java",
+    "bindings/ruby/ext/regorusrb",
 ]
 
 [package]

README.md

@@ -13,7 +13,7 @@ Regorus is also
   - *extensible* - Extend the Rego language by implementing custom stateful builtins in Rust.
     See [add_extension](https://github.com/microsoft/regorus/blob/fc68bf9c8bea36427dae9401a7d1f6ada771f7ab/src/engine.rs#L352).
     Support for extensibility using other languages coming soon.
-  - *polyglot* - In addition to Rust, Regorus can be used from *C*, *C++*, *C#*, *Golang*, *Java*, *Javascript* and *Python*.
+  - *polyglot* - In addition to Rust, Regorus can be used from *C*, *C++*, *C#*, *Golang*, *Java*, *Javascript*, *Python*, and *Ruby*.
     This is made possible by the excellent FFI tools available in the Rust ecosystem. See [bindings](#bindings) for information on how to use Regorus from different languages.
 
     To try out a *Javascript(WASM)* compiled version of Regorus from your browser, visit [Regorus Playground](https://anakrish.github.io/regorus-playground/).
@@ -90,6 +90,8 @@ Regorus can be used from a variety of languages:
 - *Javascript*: Regorus is compiled to WASM using [wasmpack](https://github.com/rustwasm/wasm-pack).
   See [bindings/wasm](https://github.com/microsoft/regorus/tree/main/bindings/wasm) for an example of using Regorus from nodejs.
   To try out a *Javascript(WASM)* compiled version of Regorus from your browser, visit [Regorus Playground](https://anakrish.github.io/regorus-playground/).
+- *Ruby*: Ruby bindings are developed using [magnus](https://github.com/matsadler/magnus).
+  See [bindings/ruby](https://github.com/microsoft/regorus/tree/main/bindings/ruby).
 
 To avoid operational overhead, we currently don't publish these bindings to various repositories.
 It is straight-forward to build these bindings yourself.

bindings/ruby/.gitignore

@@ -0,0 +1,14 @@
+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+*.bundle
+*.so
+*.o
+*.a
+mkmf.log
+target/

bindings/ruby/.rubocop.yml

@@ -0,0 +1,29 @@
+require:
+  - rubocop-minitest
+  - rubocop-rake
+
+AllCops:
+  TargetRubyVersion: 3.0
+  NewCops: enable
+
+Layout/LineLength:
+  Max: 180
+
+Lint/EmptyClass:
+  Enabled: false
+
+Metrics/ClassLength:
+  Exclude:
+    - 'test/**/*.rb'
+
+Metrics/MethodLength:
+  Enabled: false
+
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
+
+Style/StringLiteralsInInterpolation:
+  EnforcedStyle: double_quotes
+
+Style/WordArray:
+  Enabled: false

bindings/ruby/.tool-versions

@@ -0,0 +1 @@
+ruby 3.3.0

bindings/ruby/CHANGELOG.md

@@ -0,0 +1,5 @@
+## [Unreleased]
+
+## [0.1.0] - 2024-03-29
+
+- Initial release

bindings/ruby/Gemfile

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+# Specify your gem's dependencies in regorusrb.gemspec
+gemspec
+
+# These gems are required for local development and testing,
+# but won't be included in the published gem
+gem "minitest", "~> 5.16"
+gem "rake", "~> 13.0"
+gem "rake-compiler"
+gem "rb_sys", "~> 0.9.63"
+gem "rubocop", "~> 1.62", require: false
+gem "rubocop-minitest", require: false
+gem "rubocop-rake", require: false

bindings/ruby/Gemfile.lock

@@ -0,0 +1,61 @@
+PATH
+  remote: .
+  specs:
+    regorusrb (0.1.0)
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ast (2.4.2)
+    json (2.7.1)
+    language_server-protocol (3.17.0.3)
+    minitest (5.22.3)
+    parallel (1.24.0)
+    parser (3.3.0.5)
+      ast (~> 2.4.1)
+      racc
+    racc (1.7.3)
+    rainbow (3.1.1)
+    rake (13.1.0)
+    rake-compiler (1.2.7)
+      rake
+    rb_sys (0.9.90)
+    regexp_parser (2.9.0)
+    rexml (3.2.6)
+    rubocop (1.62.1)
+      json (~> 2.3)
+      language_server-protocol (>= 3.17.0)
+      parallel (~> 1.10)
+      parser (>= 3.3.0.2)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 3.0)
+    rubocop-ast (1.31.2)
+      parser (>= 3.3.0.4)
+    rubocop-minitest (0.35.0)
+      rubocop (>= 1.61, < 2.0)
+      rubocop-ast (>= 1.31.1, < 2.0)
+    rubocop-rake (0.6.0)
+      rubocop (~> 1.0)
+    ruby-progressbar (1.13.0)
+    unicode-display_width (2.5.0)
+
+PLATFORMS
+  ruby
+  x86_64-linux
+
+DEPENDENCIES
+  minitest (~> 5.16)
+  rake (~> 13.0)
+  rake-compiler
+  rb_sys (~> 0.9.63)
+  regorusrb!
+  rubocop (~> 1.62)
+  rubocop-minitest
+  rubocop-rake
+
+BUNDLED WITH
+   2.5.7

bindings/ruby/LICENSE.txt

@@ -0,0 +1 @@
+../../LICENSE

bindings/ruby/README.md

@@ -0,0 +1,95 @@
+# Regorusrb
+
+**Regorus** is
+
+  - *Rego*-*Rus(t)*  - A fast, light-weight [Rego](https://www.openpolicyagent.org/docs/latest/policy-language/)
+   interpreter written in Rust.
+  - *Rigorous* - A rigorous enforcer of well-defined Rego semantics.
+
+## Installation
+
+Regorus can be used in Ruby by configuring bundler to build from the remote git source.
+
+Use the bundler CLI to add the gem from remote git source:
+`
+bundle add regorus --git 'https://github.com/microsoft/regorus/tree/main/bindings/ruby'
+`
+
+or manually edit your gemfile to include the following
+`
+gem "regorus", git: "https://github.com/microsoft/regorus/tree/main/bindings/ruby"
+`
+
+It is not yet available in rubygems.
+
+See [Repository](https://github.com/microsoft/regorus).
+
+To build this gem locally without bundler,
+
+`rake build`
+
+then to install the gem and build the native extensions
+
+`gem install --local ./pkg/regorusrb-0.1.0.gem`
+
+## Usage
+
+```ruby
+require "regorus"
+
+engine = Regorus::Engine.new
+
+engine.add_policy_from_file('../../tests/aci/framework.rego')
+engine.add_policy_from_file('../../tests/aci/api.rego')
+engine.add_policy_from_file('../../tests/aci/policy.rego')
+
+
+# can be strings or symbols
+data = {
+  metadata: {
+    devices: {
+      "/run/layers/p0-layer0": "1b80f120dbd88e4355d6241b519c3e25290215c469516b49dece9cf07175a766",
+      "/run/layers/p0-layer1": "e769d7487cc314d3ee748a4440805317c19262c7acd2fdbdb0d47d2e4613a15c",
+      "/run/layers/p0-layer2": "eb36921e1f82af46dfe248ef8f1b3afb6a5230a64181d960d10237a08cd73c79",
+      "/run/layers/p0-layer3": "41d64cdeb347bf236b4c13b7403b633ff11f1cf94dbc7cf881a44d6da88c5156",
+      "/run/layers/p0-layer4": "4dedae42847c704da891a28c25d32201a1ae440bce2aecccfa8e6f03b97a6a6c",
+      "/run/layers/p0-layer5": "fe84c9d5bfddd07a2624d00333cf13c1a9c941f3a261f13ead44fc6a93bc0e7a"
+    }
+  }
+}
+
+engine.add_data(data)
+input = {
+  "containerID": "container0",
+  "layerPaths": [
+    "/run/layers/p0-layer0",
+    "/run/layers/p0-layer1",
+    "/run/layers/p0-layer2",
+    "/run/layers/p0-layer3",
+    "/run/layers/p0-layer4",
+    "/run/layers/p0-layer5"
+  ],
+  "target": "/run/gcs/c/container0/rootfs"
+}
+
+engine.set_input(input)
+
+# Evaluate a specife rule
+rule_results = engine.eval_rule('data.framework.mount_overlay')
+puts rule_results # { "allowed" => true, "metadata" => [...]}
+
+# Or evalute a full policy document
+query_results = engine.eval_query('data.framework')
+puts query_results[:result][0]
+
+# Query results can can also be returned as JSON strings instead of Ruby Hash structure
+results_json = engine.eval_query_as_json('data.framework.mount_overlay=x')
+puts results_json
+```
+
+## Development
+
+After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+
+To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and the created tag, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+

bindings/ruby/Rakefile

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require "bundler/gem_tasks"
+require "minitest/test_task"
+
+Minitest::TestTask.create
+
+require "rubocop/rake_task"
+
+RuboCop::RakeTask.new
+
+require "rb_sys/extensiontask"
+
+desc "build the .gem file, including native extensions, according to the .gemspec"
+task build: :compile
+
+GEMSPEC = Gem::Specification.load("regorusrb.gemspec")
+
+RbSys::ExtensionTask.new("regorusrb", GEMSPEC) do |ext|
+  ext.lib_dir = "lib/regorusrb"
+end
+
+task default: %i[compile test rubocop]

bindings/ruby/bin/console

@@ -0,0 +1,11 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "regorus"
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+require "irb"
+IRB.start(__FILE__)

bindings/ruby/bin/setup

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here

bindings/ruby/ext/regorusrb/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "regorusrb"
+version = "0.1.0"
+edition = "2021"
+description = "Ruby bindings for Regorus - a fast, lightweight Rego interpreter written in Rust"
+publish = false
+
+[lib]
+crate-type = ["cdylib"]
+path = "src/lib.rs"
+
+[dependencies]
+magnus = { version = "0.6.2" }
+regorus = { path = "../../../.." }
+serde_json = "1.0.115"
+serde_magnus = "0.8.1"

bindings/ruby/ext/regorusrb/extconf.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+require "mkmf"
+require "rb_sys/mkmf"
+
+create_rust_makefile("regorusrb/regorusrb")

bindings/ruby/ext/regorusrb/src/lib.rs

@@ -0,0 +1,224 @@
+use magnus::{exception::runtime_error, method, module, prelude::*, Error, Ruby};
+use regorus::Engine as RegorusEngine;
+use std::cell::RefCell;
+use std::cmp::Ordering;
+
+// `Value` exists under magnus, regorus, and serde_json, so be explicit
+
+#[derive(Default)]
+#[magnus::wrap(class = "Regorus::Engine")]
+pub struct Engine {
+    engine: RefCell<RegorusEngine>,
+}
+
+impl Clone for Engine {
+    fn clone(&self) -> Self {
+        Self {
+            engine: self.engine.clone(),
+        }
+    }
+}
+
+impl Engine {
+    fn initialize(&self) {
+        let engine = RegorusEngine::new();
+        *self.engine.borrow_mut() = engine;
+    }
+
+    fn compare(&self, other: &Self) -> Result<i32, Error> {
+        let self_ptr: *const _ = &*self.engine.borrow();
+        let other_ptr: *const _ = &*other.engine.borrow();
+        match self_ptr.partial_cmp(&other_ptr) {
+            Some(Ordering::Less) => Ok(-1),
+            Some(Ordering::Equal) => Ok(0),
+            Some(Ordering::Greater) => Ok(1),
+            None => Err(Error::new(runtime_error(), "Comparison failed")),
+        }
+    }
+
+    fn add_policy(&self, path: String, rego: String) -> Result<(), Error> {
+        self.engine
+            .borrow_mut()
+            .add_policy(path, rego)
+            .map_err(|e| Error::new(runtime_error(), format!("Failed to add policy: {}", e)))
+    }
+
+    fn add_policy_from_file(&self, path: String) -> Result<(), Error> {
+        self.engine
+            .borrow_mut()
+            .add_policy_from_file(path)
+            .map_err(|e| Error::new(runtime_error(), format!("Failed to add policy: {}", e)))
+    }
+
+    fn add_data(&self, ruby_hash: magnus::RHash) -> Result<(), Error> {
+        let data_value: regorus::Value = serde_magnus::deserialize(ruby_hash).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to deserialize Ruby value: {}", e),
+            )
+        })?;
+
+        self.engine
+            .borrow_mut()
+            .add_data(data_value)
+            .map_err(|e| Error::new(runtime_error(), format!("Failed to add data: {}", e)))
+    }
+
+    fn add_data_json(&self, json_string: String) -> Result<(), Error> {
+        self.engine
+            .borrow_mut()
+            .add_data_json(&json_string)
+            .map_err(|e| Error::new(runtime_error(), format!("Failed to add data json: {}", e)))
+    }
+
+    fn add_data_from_json_file(&self, path: String) -> Result<(), Error> {
+        let json_data = regorus::Value::from_json_file(&path).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to parse JSON data file: {}", e),
+            )
+        })?;
+
+        self.engine.borrow_mut().add_data(json_data).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to add data from file: {}", e),
+            )
+        })
+    }
+
+    fn clear_data(&self) -> Result<(), Error> {
+        self.engine.borrow_mut().clear_data();
+        Ok(())
+    }
+
+    fn set_input(&self, ruby_hash: magnus::RHash) -> Result<(), Error> {
+        let input_value: regorus::Value = serde_magnus::deserialize(ruby_hash).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to deserialize Ruby value: {}", e),
+            )
+        })?;
+
+        self.engine.borrow_mut().set_input(input_value);
+        Ok(())
+    }
+
+    fn set_input_json(&self, json_string: String) -> Result<(), Error> {
+        self.engine
+            .borrow_mut()
+            .set_input_json(&json_string)
+            .map_err(|e| Error::new(runtime_error(), format!("Failed to set input JSON: {}", e)))
+    }
+
+    fn add_input_from_json_file(&self, path: String) -> Result<(), Error> {
+        let json_data = regorus::Value::from_json_file(&path).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to parse JSON input file: {}", e),
+            )
+        })?;
+
+        self.engine.borrow_mut().set_input(json_data);
+        Ok(())
+    }
+
+    fn eval_query(&self, query: String) -> Result<magnus::Value, Error> {
+        let results = self
+            .engine
+            .borrow_mut()
+            .eval_query(query, false)
+            .map_err(|e| Error::new(runtime_error(), format!("Failed to evaluate query: {}", e)))?;
+
+        serde_magnus::serialize(&results).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to serailzie query results: {}", e),
+            )
+        })
+    }
+
+    fn eval_query_as_json(&self, query: String) -> Result<String, Error> {
+        let results = self
+            .engine
+            .borrow_mut()
+            .eval_query(query, false)
+            .map_err(|e| {
+                Error::new(
+                    runtime_error(),
+                    format!("Failed to evaluate query as json: {}", e),
+                )
+            })?;
+
+        serde_json::to_string(&results).map_err(|e| {
+            Error::new(
+                runtime_error(),
+                format!("Failed to serialize query results: {}", e),
+            )
+        })
+    }
+
+    fn eval_rule(&self, path: String) -> Result<Option<magnus::Value>, Error> {
+        let result =
+            self.engine.borrow_mut().eval_rule(path).map_err(|e| {
+                Error::new(runtime_error(), format!("Failed to evaluate rule: {}", e))
+            })?;
+
+        match result {
+            regorus::Value::Undefined => Ok(None), // Convert undefined to Ruby's nil
+            _ => serde_magnus::serialize(&result) // Serialize other results normally
+                .map(Some)
+                .map_err(|e| {
+                    magnus::Error::new(
+                        runtime_error(),
+                        format!("Failed to serialize the rule evaluation result: {}", e),
+                    )
+                }),
+        }
+    }
+}
+
+#[magnus::init]
+fn init(ruby: &Ruby) -> Result<(), Error> {
+    let regorus_module = ruby.define_module("Regorus")?;
+    let engine_class = regorus_module.define_class("Engine", ruby.class_object())?;
+
+    // ruby object methods
+    engine_class.define_alloc_func::<Engine>();
+    engine_class.define_method("initialize", method!(Engine::initialize, 0))?;
+    engine_class.define_method("clone", method!(Engine::clone, 0))?;
+    engine_class.define_method("<=>", method!(Engine::compare, 1))?;
+    // defines <, <=, >, >=, and == based on <=>
+    engine_class.include_module(module::comparable())?;
+
+    // policy operations
+    engine_class.define_method("add_policy", method!(Engine::add_policy, 2))?;
+    engine_class.define_method(
+        "add_policy_from_file",
+        method!(Engine::add_policy_from_file, 1),
+    )?;
+
+    // data operations
+    engine_class.define_method("add_data", method!(Engine::add_data, 1))?;
+    engine_class.define_method("add_data_json", method!(Engine::add_data_json, 1))?;
+    engine_class.define_method(
+        "add_data_from_json_file",
+        method!(Engine::add_data_from_json_file, 1),
+    )?;
+    engine_class.define_method("clear_data", method!(Engine::clear_data, 0))?;
+
+    // input operations
+    engine_class.define_method("set_input", method!(Engine::set_input, 1))?;
+    engine_class.define_method("set_input_json", method!(Engine::set_input_json, 1))?;
+    engine_class.define_method(
+        "add_input_from_json_file",
+        method!(Engine::add_input_from_json_file, 1),
+    )?;
+
+    // query operations
+    engine_class.define_method("eval_query", method!(Engine::eval_query, 1))?;
+    engine_class.define_method("eval_query_as_json", method!(Engine::eval_query_as_json, 1))?;
+    engine_class.define_method("eval_rule", method!(Engine::eval_rule, 1))?;
+
+    Ok(())
+}

bindings/ruby/lib/regorus.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+require_relative "regorus/version"
+require_relative "regorusrb/regorusrb"
+
+module Regorus
+  class Engine; end
+end

bindings/ruby/lib/regorus/version.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+module Regorus
+  VERSION = "0.1.0"
+end

bindings/ruby/regorusrb.gemspec

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require_relative "lib/regorus/version"
+
+Gem::Specification.new do |spec|
+  spec.name = "regorusrb"
+  spec.version = Regorus::VERSION
+  spec.authors = ["David Marshall"]
+
+  spec.summary = "Ruby bindings for Regorus - a fast, lightweight Rego interpreter written in Rust"
+  spec.homepage = "https://github.com/microsoft/regorus/blob/main/bindings/ruby"
+  spec.license = "MIT"
+  spec.required_ruby_version = ">= 3.0.0"
+  spec.required_rubygems_version = ">= 3.3.11"
+
+  spec.metadata["allowed_push_host"] = "TODO: Set to your gem server 'https://example.com'"
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+  spec.metadata["changelog_uri"] = "#{spec.homepage}/blob/main/bindings/ruby/CHANGELOG.md"
+  spec.metadata["rubygems_mfa_required"] = "true"
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  gemspec = File.basename(__FILE__)
+  spec.files = IO.popen(%w[git ls-files -z], chdir: __dir__, err: IO::NULL) do |ls|
+    ls.readlines("\x0", chomp: true).reject do |f|
+      (f == gemspec) ||
+        f.start_with?(*%w[bin/ test/ spec/ features/ .git .github appveyor Gemfile])
+    end
+  end
+
+  # Ensure Cargo.lock is included
+  spec.files << "../../Cargo.lock" if File.exist?("../../Cargo.lock")
+
+  spec.bindir = "exe"
+  spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+  spec.extensions = ["ext/regorusrb/Cargo.toml"]
+end

bindings/ruby/sig/regorusrb.rbs

@@ -0,0 +1,4 @@
+module Regorus
+  VERSION: String
+  # See the writing guide of rbs: https://github.com/ruby/rbs#guides
+end

bindings/ruby/test/test_helper.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+$LOAD_PATH.unshift File.expand_path("../lib", __dir__)
+require "regorus"
+
+require "minitest/autorun"

bindings/ruby/test/test_regorus.rb

@@ -0,0 +1,180 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "json"
+
+class TestRegorus < Minitest::Test
+  ALICE = "Alice"
+  BOB = "Bob"
+  CARLOS = "Carlos"
+
+  def setup
+    @engine = ::Regorus::Engine.new
+    @engine.add_policy("regorus_test.rego", example_policy)
+    @engine.add_data(example_data)
+  end
+
+  def example_policy
+    <<~REGO
+      package regorus_test
+      is_manager {
+        input.name == data.managers[_]
+      }
+
+      is_employee {
+        input.name == data.employees[_]
+      }
+
+      # Set a default value for to return false instead of nil
+      default is_manager_bool = false
+      default is_employee_bool = false
+
+      is_manager_bool {
+        is_manager
+      }
+
+      is_employee_bool {
+        is_employee
+      }
+    REGO
+  end
+
+  def example_data
+    {
+      "managers" => [ALICE],
+      "employees" => [ALICE, BOB]
+    }
+  end
+
+  def input_for(name)
+    { "name" => name }
+  end
+
+  def test_version_number_presence
+    refute_nil ::Regorus::VERSION
+  end
+
+  def test_engine_creation
+    assert_instance_of ::Regorus::Engine, ::Regorus::Engine.new
+  end
+
+  def test_policy_addition
+    assert_silent { @engine.add_policy("example.rego", example_policy) }
+  end
+
+  def test_object_creation_with_new
+    refute_same ::Regorus::Engine.new, ::Regorus::Engine.new
+  end
+
+  def test_data_addition
+    assert_silent { @engine.add_data(example_data) }
+  end
+
+  def test_data_addition_as_json
+    assert_silent { @engine.add_data_json(example_data.to_json) }
+  end
+
+  def test_query_evaluation_for_alice
+    @engine.set_input(input_for(ALICE))
+
+    assert_equal alice_results, @engine.eval_query("data.regorus_test")
+  end
+
+  def test_query_evaluation_for_bob
+    @engine.set_input(input_for(BOB))
+
+    assert_equal bob_results, @engine.eval_query("data.regorus_test")
+  end
+
+  def test_query_evaluation_as_json
+    @engine.set_input(input_for(ALICE))
+
+    assert_equal alice_results.to_json, @engine.eval_query_as_json("data.regorus_test")
+  end
+
+  def test_rule_evaluation_for_alice
+    @engine.set_input(input_for(ALICE))
+
+    assert @engine.eval_rule("data.regorus_test.is_employee")
+    assert @engine.eval_rule("data.regorus_test.is_employee_bool")
+    assert @engine.eval_rule("data.regorus_test.is_manager")
+    assert @engine.eval_rule("data.regorus_test.is_manager_bool")
+  end
+
+  def test_rule_evaluation_for_bob
+    @engine.set_input(input_for(BOB))
+
+    assert @engine.eval_rule("data.regorus_test.is_employee")
+    assert @engine.eval_rule("data.regorus_test.is_employee_bool")
+    assert_nil @engine.eval_rule("data.regorus_test.is_manager")
+    refute @engine.eval_rule("data.regorus_test.is_manager_bool")
+  end
+
+  def test_rule_evaluation_for_carlos
+    @engine.set_input(input_for(CARLOS))
+
+    assert_nil @engine.eval_rule("data.regorus_test.is_employee")
+    refute @engine.eval_rule("data.regorus_test.is_employee_bool")
+    assert_nil @engine.eval_rule("data.regorus_test.is_manager")
+    refute @engine.eval_rule("data.regorus_test.is_manager_bool")
+  end
+
+  def test_missing_rules_handling
+    @engine.set_input(input_for(ALICE))
+    assert_raises(RuntimeError) { @engine.eval_rule("data.regorus_test.not_a_rule") }
+  end
+
+  def test_engine_cloning
+    cloned_engine = @engine.clone
+
+    assert_instance_of ::Regorus::Engine, cloned_engine
+    refute_same @engine, cloned_engine
+  end
+
+  def alice_results
+    {
+      result: [
+        {
+          expressions: [
+            {
+              value: {
+                "is_employee" => true,
+                "is_employee_bool" => true,
+                "is_manager" => true,
+                "is_manager_bool" => true
+              },
+              text: "data.regorus_test",
+              location: {
+                row: 1,
+                col: 1
+              }
+            }
+          ]
+        }
+      ]
+    }
+  end
+
+  def bob_results
+    {
+      result: [
+        {
+          expressions: [
+            {
+              value: {
+                "is_employee" => true,
+                "is_employee_bool" => true,
+                "is_manager_bool" => false
+              },
+              text: "data.regorus_test",
+              location: {
+                row: 1,
+                col: 1
+              }
+            }
+          ]
+        }
+      ]
+    }
+  end
+end