telescope.nvim/lua/tests/automated/linked_list_spec.lua

local LinkedList = require('telescope.algos.linked_list')

local eq = assert.are.same

describe('LinkedList', function()
  it('can create a list', function()
    local l = LinkedList:new()

    assert.are.same(0, l.size)
  end)

  it('can add a single entry to the list', function()
    local l = LinkedList:new()
    l:append('hello')

    assert.are.same(1, l.size)
  end)

  it('can iterate over one item', function()
    local l = LinkedList:new()
    l:append('hello')

    for val in l:iter() do
      assert.are.same('hello', val)
    end
  end)

  it('iterates in order', function()
    local l = LinkedList:new()
    l:append('hello')
    l:append('world')

    local x = {}
    for val in l:iter() do
      table.insert(x, val)
    end

    assert.are.same({'hello', 'world'}, x)
  end)

  it('iterates in order, for prepend', function()
    local l = LinkedList:new()
    l:prepend('world')
    l:prepend('hello')

    local x = {}
    for val in l:iter() do
      table.insert(x, val)
    end

    assert.are.same({'hello', 'world'}, x)
  end)

  it('iterates in order, for combo', function()
    local l = LinkedList:new()
    l:prepend('world')
    l:prepend('hello')
    l:append('last')
    l:prepend('first')

    local x = {}
    for val in l:iter() do
      table.insert(x, val)
    end

    assert.are.same({'first', 'hello', 'world', 'last'}, x)
    assert.are.same(#x, l.size)
  end)

  it('has ipairs', function()
    local l = LinkedList:new()
    l:prepend('world')
    l:prepend('hello')
    l:append('last')
    l:prepend('first')

    local x = {}
    for v in l:iter() do
      table.insert(x, v)
    end
    assert.are.same({'first', 'hello', 'world', 'last'}, x)

    local expected = {}
    for i, v in ipairs(x) do
      table.insert(expected, {i, v})
    end

    local actual = {}
    for i, v in l:ipairs() do
      table.insert(actual, {i, v})
    end

    assert.are.same(expected, actual)
  end)

  describe('track_at', function()
    it('should update tracked when only appending', function()
      local l = LinkedList:new { track_at = 2 }
      l:append("first")
      l:append("second")
      l:append("third")

      assert.are.same("second", l.tracked)
    end)

    it('should update tracked when first some prepend and then append', function()
      local l = LinkedList:new { track_at = 2 }
      l:prepend("first")
      l:append("second")
      l:append("third")

      assert.are.same("second", l.tracked)
    end)

    it('should update when only prepending', function()
      local l = LinkedList:new { track_at = 2 }
      l:prepend("third")
      l:prepend("second")
      l:prepend("first")

      assert.are.same("second", l.tracked)
    end)

    it('should update when lots of prepend and append', function()
      local l = LinkedList:new { track_at = 2 }
      l:prepend("third")
      l:prepend("second")
      l:prepend("first")
      l:append("fourth")
      l:prepend("zeroth")

      assert.are.same("first", l.tracked)
    end)

    describe(':shift()', function()
      it('should return nil for empty list', function()
        local l = LinkedList:new()

        eq(nil, l:shift())
      end)

      it('should return the first element, and then nothing if length 1', function()
        local l = LinkedList:new { track_at = 2 }
        l:append('hello')

        eq('hello', l:shift())
        eq(0, l.size)

        eq(nil, l:shift())
      end)

      it('should return each element', function()
        local l = LinkedList:new { track_at = 2 }
        l:append('hello')
        l:append('world')
        l:append('last')

        eq('hello', l:shift())
        eq('world', l:shift())

        eq(1, l.size)
      end)
    end)

    describe(':pop()', function()
      it('should return nil for empty list', function()
        local l = LinkedList:new()

        eq(nil, l:pop())
      end)

      it('should return the first element, and then nothing if length 1', function()
        local l = LinkedList:new { track_at = 2 }
        l:append('hello')

        eq('hello', l:pop())
        eq(0, l.size)

        eq(nil, l:pop())
      end)

      it('should return each element', function()
        local l = LinkedList:new { track_at = 2 }
        l:append('hello')
        l:append('world')
        l:append('last')

        eq('last', l:pop())
        eq('world', l:pop())

        eq(1, l.size)
      end)
    end)
  end)
end)