Update linked-list tests (#587)

Author: ryanplusplus

exercises/practice/linked-list/.meta/example.lua

@@ -15,7 +15,9 @@ end
 function LinkedList:pop()
   local v = self._head.v
   self._head = self._head.next
-  if not self._head then
+  if self._head then
+    self._head.prev = nil
+  else
     self._tail = nil
   end
   return v
@@ -37,6 +39,8 @@ function LinkedList:shift()
   self._tail = self._tail.prev
   if self._tail then
     self._tail.next = nil
+  else
+    self._head = nil
   end
   return v
 end
@@ -52,21 +56,21 @@ function LinkedList:count()
 end
 
 function LinkedList:delete(v)
+  if self._head.v == v then
+    self:pop()
+    return
+  end
+
   local current = self._head
   while current do
     if current.v == v then
-      if self._head == current then
-        self._head = current.next
-      end
-      if self._tail == current then
-        self._tail = current.prev
-      end
       if current.prev then
         current.prev.next = current.next
       end
       if current.next then
         current.next.prev = current.prev
       end
+      return
     end
     current = current.next
   end

exercises/practice/linked-list/.meta/spec_generator.lua

@@ -0,0 +1,19 @@
+return {
+  module_name = 'LinkedList',
+
+  generate_test = function(case)
+    local lines = { 'local list = LinkedList()' }
+
+    for _, operation in ipairs(case.input.operations) do
+      if operation.value then
+        table.insert(lines, ('list:%s(%s)'):format(operation.operation, operation.value))
+      elseif operation.expected then
+        table.insert(lines, ('assert.equal(%s, list:%s())'):format(operation.expected, operation.operation))
+      else
+        table.insert(lines, ('list:%s()'):format(operation.operation))
+      end
+    end
+
+    return table.concat(lines, '\n')
+  end
+}

exercises/practice/linked-list/.meta/tests.toml

@@ -0,0 +1,67 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[7f7e3987-b954-41b8-8084-99beca08752c]
+description = "pop gets element from the list"
+
+[c3f67e5d-cfa2-4c3e-a18f-7ce999c3c885]
+description = "push/pop respectively add/remove at the end of the list"
+
+[00ea24ce-4f5c-4432-abb4-cc6e85462657]
+description = "shift gets an element from the list"
+
+[37962ee0-3324-4a29-b588-5a4c861e6564]
+description = "shift gets first element from the list"
+
+[30a3586b-e9dc-43fb-9a73-2770cec2c718]
+description = "unshift adds element at start of the list"
+
+[042f71e4-a8a7-4cf0-8953-7e4f3a21c42d]
+description = "pop, push, shift, and unshift can be used in any order"
+
+[88f65c0c-4532-4093-8295-2384fb2f37df]
+description = "count an empty list"
+
+[fc055689-5cbe-4cd9-b994-02e2abbb40a5]
+description = "count a list with items"
+
+[8272cef5-130d-40ea-b7f6-5ffd0790d650]
+description = "count is correct after mutation"
+
+[229b8f7a-bd8a-4798-b64f-0dc0bb356d95]
+description = "popping to empty doesn't break the list"
+
+[4e1948b4-514e-424b-a3cf-a1ebbfa2d1ad]
+description = "shifting to empty doesn't break the list"
+
+[e8f7c600-d597-4f79-949d-8ad8bae895a6]
+description = "deletes the only element"
+
+[fd65e422-51f3-45c0-9fd0-c33da638f89b]
+description = "deletes the element with the specified value from the list"
+
+[59db191a-b17f-4ab7-9c5c-60711ec1d013]
+description = "deletes the element with the specified value from the list, re-assigns tail"
+
+[58242222-5d39-415b-951d-8128247f8993]
+description = "deletes the element with the specified value from the list, re-assigns head"
+
+[ee3729ee-3405-4bd2-9bad-de0d4aa5d647]
+description = "deletes the first of two elements"
+
+[47e3b3b4-b82c-4c23-8c1a-ceb9b17cb9fb]
+description = "deletes the second of two elements"
+
+[7b420958-f285-4922-b8f9-10d9dcab5179]
+description = "delete does not modify the list if the element is not found"
+
+[7e04828f-6082-44e3-a059-201c63252a76]
+description = "deletes only the first occurrence"

exercises/practice/linked-list/linked-list_spec.lua

@@ -1,113 +1,177 @@
 local LinkedList = require('linked-list')
 
 describe('linked-list', function()
-  it('should be able to pop pushed elements', function()
+  it('pop gets element from the list', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
-    assert.equal(20, list:pop())
-    assert.equal(10, list:pop())
+    list:push(7)
+    assert.equal(7, list:pop())
   end)
 
-  it('should be able to shift pushed elements', function()
+  it('push/pop respectively add/remove at the end of the list', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
-    assert.equal(10, list:shift())
-    assert.equal(20, list:shift())
+    list:push(11)
+    list:push(13)
+    assert.equal(13, list:pop())
+    assert.equal(11, list:pop())
   end)
 
-  it('should be able to shift unshifted elements', function()
+  it('shift gets an element from the list', function()
     local list = LinkedList()
-    list:unshift(10)
-    list:unshift(20)
-    assert.equal(20, list:shift())
-    assert.equal(10, list:shift())
+    list:push(17)
+    assert.equal(17, list:shift())
   end)
 
-  it('should be able to pop unshifted elements', function()
+  it('shift gets first element from the list', function()
     local list = LinkedList()
-    list:unshift(10)
-    list:unshift(20)
-    assert.equal(10, list:pop())
-    assert.equal(20, list:pop())
+    list:push(23)
+    list:push(5)
+    assert.equal(23, list:shift())
+    assert.equal(5, list:shift())
   end)
 
-  it('should be able to count its elements', function()
+  it('unshift adds element at start of the list', function()
+    local list = LinkedList()
+    list:unshift(23)
+    list:unshift(5)
+    assert.equal(5, list:shift())
+    assert.equal(23, list:shift())
+  end)
+
+  it('pop, push, shift, and unshift can be used in any order', function()
+    local list = LinkedList()
+    list:push(1)
+    list:push(2)
+    assert.equal(2, list:pop())
+    list:push(3)
+    assert.equal(1, list:shift())
+    list:unshift(4)
+    list:push(5)
+    assert.equal(4, list:shift())
+    assert.equal(5, list:pop())
+    assert.equal(3, list:shift())
+  end)
+
+  it('count an empty list', function()
     local list = LinkedList()
     assert.equal(0, list:count())
-    list:push(10)
-    assert.equal(1, list:count())
-    list:push(20)
-    assert.equal(2, list:count())
+  end)
 
+  it('count a list with items', function()
+    local list = LinkedList()
+    list:push(37)
+    list:push(1)
+    assert.equal(2, list:count())
   end)
 
-  it('should count correctly after a shift', function()
+  it('count is correct after mutation', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
+    list:push(31)
+    assert.equal(1, list:count())
+    list:unshift(43)
+    assert.equal(2, list:count())
     list:shift()
     assert.equal(1, list:count())
+    list:pop()
+    assert.equal(0, list:count())
   end)
 
-  it('should count correctly after a pop', function()
+  it('popping to empty doesn\'t break the list', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
+    list:push(41)
+    list:push(59)
     list:pop()
+    list:pop()
+    list:push(47)
     assert.equal(1, list:count())
+    assert.equal(47, list:pop())
   end)
 
-  it('should be able to delete from the beginning of the list', function()
+  it('shifting to empty doesn\'t break the list', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
-    list:push(30)
-    list:delete(30)
-    assert.equal(2, list:count())
-    assert.equal(20, list:pop())
-    assert.equal(10, list:shift())
+    list:push(41)
+    list:push(59)
+    list:shift()
+    list:shift()
+    list:push(47)
+    assert.equal(1, list:count())
+    assert.equal(47, list:shift())
+  end)
+
+  it('deletes the only element', function()
+    local list = LinkedList()
+    list:push(61)
+    list:delete(61)
+    assert.equal(0, list:count())
   end)
 
-  it('should be able to delete from the middle of the list', function()
+  it('deletes the element with the specified value from the list', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
-    list:push(30)
-    list:delete(20)
+    list:push(71)
+    list:push(83)
+    list:push(79)
+    list:delete(83)
     assert.equal(2, list:count())
-    assert.equal(30, list:pop())
-    assert.equal(10, list:shift())
+    assert.equal(79, list:pop())
+    assert.equal(71, list:shift())
   end)
 
-  it('should be able to delete from the end of the list', function()
+  it('deletes the element with the specified value from the list, re-assigns tail', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
-    list:push(30)
-    list:delete(10)
+    list:push(71)
+    list:push(83)
+    list:push(79)
+    list:delete(83)
     assert.equal(2, list:count())
-    assert.equal(30, list:pop())
-    assert.equal(20, list:shift())
+    assert.equal(79, list:pop())
+    assert.equal(71, list:pop())
   end)
 
-  it('should delete all elements with the matching value', function()
+  it('deletes the element with the specified value from the list, re-assigns head', function()
     local list = LinkedList()
-    list:push(10)
-    list:push(20)
-    list:push(20)
-    list:push(30)
-    list:delete(20)
+    list:push(71)
+    list:push(83)
+    list:push(79)
+    list:delete(83)
     assert.equal(2, list:count())
-    assert.equal(30, list:pop())
-    assert.equal(10, list:shift())
+    assert.equal(71, list:shift())
+    assert.equal(79, list:shift())
   end)
 
-  it('should be able to delete the only element', function()
+  it('deletes the first of two elements', function()
     local list = LinkedList()
-    list:push(10)
-    list:delete(10)
-    assert.equal(0, list:count())
+    list:push(97)
+    list:push(101)
+    list:delete(97)
+    assert.equal(1, list:count())
+    assert.equal(101, list:pop())
+  end)
+
+  it('deletes the second of two elements', function()
+    local list = LinkedList()
+    list:push(97)
+    list:push(101)
+    list:delete(101)
+    assert.equal(1, list:count())
+    assert.equal(97, list:pop())
+  end)
+
+  it('delete does not modify the list if the element is not found', function()
+    local list = LinkedList()
+    list:push(89)
+    list:delete(103)
+    assert.equal(1, list:count())
+  end)
+
+  it('deletes only the first occurrence', function()
+    local list = LinkedList()
+    list:push(73)
+    list:push(9)
+    list:push(9)
+    list:push(107)
+    list:delete(9)
+    assert.equal(3, list:count())
+    assert.equal(107, list:pop())
+    assert.equal(9, list:pop())
+    assert.equal(73, list:pop())
   end)
 end)