ReefVM/tests/scope.test.ts

import { test, expect } from "bun:test"
import { Scope, toValue } from "#reef"

test("Scope - create empty scope", () => {
  const scope = new Scope()
  expect(scope.parent).toBeUndefined()
  expect(scope.locals.size).toBe(0)
})

test("Scope - create child scope with parent", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  expect(child.parent).toBe(parent)
  expect(child.locals.size).toBe(0)
})

test("Scope - set and get variable in same scope", () => {
  const scope = new Scope()
  const value = toValue(42)

  scope.set("x", value)
  expect(scope.get("x")).toBe(value)
})

test("Scope - get returns undefined for non-existent variable", () => {
  const scope = new Scope()
  expect(scope.get("x")).toBeUndefined()
})

test("Scope - set updates existing variable in same scope", () => {
  const scope = new Scope()

  scope.set("x", toValue(10))
  expect(scope.get("x")).toEqual({ type: "number", value: 10 })

  scope.set("x", toValue(20))
  expect(scope.get("x")).toEqual({ type: "number", value: 20 })
})

test("Scope - get searches parent scope", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(42))
  expect(child.get("x")).toEqual({ type: "number", value: 42 })
})

test("Scope - get searches multiple levels up", () => {
  const grandparent = new Scope()
  const parent = new Scope(grandparent)
  const child = new Scope(parent)

  grandparent.set("x", toValue(100))
  expect(child.get("x")).toEqual({ type: "number", value: 100 })
})

test("Scope - child updates parent variable when it exists (no shadowing)", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(10))
  child.set("x", toValue(20))

  // set() updates parent's variable, not shadow it
  expect(parent.get("x")).toEqual({ type: "number", value: 20 })
  expect(child.get("x")).toEqual({ type: "number", value: 20 })
  expect(child.locals.has("x")).toBe(false)
})

test("Scope - set updates parent scope variable when it exists", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(10))
  child.set("x", toValue(20))

  // Should update parent's variable, not create new local one
  expect(parent.get("x")).toEqual({ type: "number", value: 20 })
  expect(child.get("x")).toEqual({ type: "number", value: 20 })
  expect(child.locals.has("x")).toBe(false)
})

test("Scope - set creates new local variable when not found in parent", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(10))
  child.set("y", toValue(20))

  expect(parent.get("x")).toEqual({ type: "number", value: 10 })
  expect(parent.get("y")).toBeUndefined()
  expect(child.get("x")).toEqual({ type: "number", value: 10 })
  expect(child.get("y")).toEqual({ type: "number", value: 20 })
  expect(child.locals.has("y")).toBe(true)
})

test("Scope - has returns true for variable in current scope", () => {
  const scope = new Scope()
  scope.set("x", toValue(42))

  expect(scope.has("x")).toBe(true)
  expect(scope.has("y")).toBe(false)
})

test("Scope - has returns true for variable in parent scope", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(42))

  expect(child.has("x")).toBe(true)
  expect(child.has("y")).toBe(false)
})

test("Scope - has searches multiple levels up", () => {
  const grandparent = new Scope()
  const parent = new Scope(grandparent)
  const child = new Scope(parent)

  grandparent.set("x", toValue(100))

  expect(child.has("x")).toBe(true)
  expect(parent.has("x")).toBe(true)
  expect(grandparent.has("x")).toBe(true)
})

test("Scope.vars() - returns empty array for empty scope", () => {
  const scope = new Scope()
  expect(scope.vars()).toEqual([])
})

test("Scope.vars() - returns single variable from current scope", () => {
  const scope = new Scope()
  scope.set("x", toValue(42))

  expect(scope.vars()).toEqual(["x"])
})

test("Scope.vars() - returns multiple variables from current scope", () => {
  const scope = new Scope()
  scope.set("x", toValue(1))
  scope.set("y", toValue(2))
  scope.set("z", toValue(3))

  const vars = scope.vars()
  expect(vars.length).toBe(3)
  expect(vars).toContain("x")
  expect(vars).toContain("y")
  expect(vars).toContain("z")
})

test("Scope.vars() - includes variables from parent scope", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(1))
  child.set("y", toValue(2))

  const vars = child.vars()
  expect(vars.length).toBe(2)
  expect(vars).toContain("x")
  expect(vars).toContain("y")
})

test("Scope.vars() - includes variables from multiple parent scopes", () => {
  const grandparent = new Scope()
  const parent = new Scope(grandparent)
  const child = new Scope(parent)

  grandparent.set("x", toValue(1))
  parent.set("y", toValue(2))
  child.set("z", toValue(3))

  const vars = child.vars()
  expect(vars.length).toBe(3)
  expect(vars).toContain("x")
  expect(vars).toContain("y")
  expect(vars).toContain("z")
})

test("Scope.vars() - no duplicates when child updates parent variable", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(10))
  child.set("x", toValue(20))  // Updates parent, doesn't create local

  // Only one "x" since child doesn't have its own local x
  const vars = child.vars()
  expect(vars).toEqual(["x"])
})

test("Scope.vars() - can't have duplicates if manually set in locals", () => {
  const parent = new Scope()
  const child = new Scope(parent)

  parent.set("x", toValue(10))
  child.locals.set("x", toValue(20))
  const vars = child.vars()
  expect(vars).toEqual(["x"])

  expect(child.get("x")).toEqual({ type: "number", value: 20 })
  expect(parent.get("x")).toEqual({ type: "number", value: 10 })
})

test("Scope.vars() - handles deep scope chains", () => {
  let scope = new Scope()

  // Create a deep chain: level0 -> level1 -> ... -> level5
  for (let i = 0; i < 5; i++) {
    scope.set(`var${i}`, toValue(i))
    scope = new Scope(scope)
  }

  // Final scope should have all variables from the chain
  const vars = scope.vars()
  expect(vars.length).toBe(5)
  expect(vars).toContain("var0")
  expect(vars).toContain("var1")
  expect(vars).toContain("var2")
  expect(vars).toContain("var3")
  expect(vars).toContain("var4")
})

test("Scope - can store and retrieve functions", () => {
  const scope = new Scope()

  const fnValue = {
    type: 'function' as const,
    value: '<function>' as const,
    params: ['x'],
    defaults: {},
    body: 0,
    variadic: false,
    named: false,
    parentScope: scope
  }

  scope.set("myFunc", fnValue)
  expect(scope.get("myFunc")).toBe(fnValue)
  expect(scope.get("myFunc")?.type).toBe("function")
})