1 files changed, 334 insertions, 0 deletions
diff --git a/test/diagnostics/cast-local-type.lua b/test/diagnostics/cast-local-type.lua
new file mode 100644
index 00000000..f79bf48d
--- /dev/null
+++ b/test/diagnostics/cast-local-type.lua
@@ -0,0 +1,334 @@
+TEST [[
+local x = 0
+
+<!x!> = true
+]]
+
+TEST [[
+---@type integer
+local x
+
+<!x!> = true
+]]
+
+TEST [[
+---@type unknown
+local x
+
+x = nil
+]]
+
+TEST [[
+---@type unknown
+local x
+
+x = 1
+]]
+
+TEST [[
+---@type unknown|nil
+local x
+
+x = 1
+]]
+
+TEST [[
+local x = {}
+
+x = nil
+]]
+
+TEST [[
+---@type string
+local x
+
+<?x?> = nil
+]]
+
+TEST [[
+---@type string?
+local x
+
+x = nil
+]]
+
+TEST [[
+---@type table
+local x
+
+<!x!> = nil
+]]
+
+TEST [[
+local x
+
+x = nil
+]]
+
+TEST [[
+---@type integer
+local x
+
+---@type number
+<!x!> = f()
+]]
+
+TEST [[
+---@type number
+local x
+
+---@type integer
+x = f()
+]]
+
+TEST [[
+---@type number|boolean
+local x
+
+---@type string
+<!x!> = f()
+]]
+
+TEST [[
+---@type number|boolean
+local x
+
+---@type boolean
+x = f()
+]]
+
+TEST [[
+---@type number|boolean
+local x
+
+---@type boolean|string
+<!x!> = f()
+]]
+
+TEST [[
+---@type boolean
+local x
+
+if not x then
+    return
+end
+
+x = f()
+]]
+
+TEST [[
+---@type boolean
+local x
+
+---@type integer
+local y
+
+<!x!> = y
+]]
+
+TEST [[
+local y = true
+
+local x
+x = 1
+x = y
+]]
+
+TEST [[
+local t = {}
+
+local x = 0
+x = x + #t
+]]
+
+TEST [[
+local x = 0
+
+x = 1.0
+]]
+
+TEST [[
+---@class A
+
+local t = {}
+
+---@type A
+local a
+
+t = a
+]]
+
+TEST [[
+---@type integer
+local x
+
+x = 1.0
+]]
+
+TEST [[
+---@type integer
+local x
+
+<!x!> = 1.5
+]]
+
+TEST [[
+---@type integer
+local x
+
+x = 1 + G
+]]
+
+TEST [[
+---@type integer
+local x
+
+x = 1 + G
+]]
+
+TEST [[
+---@alias A integer
+
+---@type A
+local a
+
+---@type integer
+local b
+
+b = a
+]]
+
+TEST [[
+---@type string[]
+local t
+
+<!t!> = 'xxx'
+]]
+
+TEST [[
+---@type 1|2
+local x
+
+x = 1
+x = 2
+<!x!> = 3
+]]
+
+TEST [[
+---@type 'x'|'y'
+local x
+
+x = 'x'
+x = 'y'
+<!x!> = 'z'
+]]
+
+TEST [[
+local t = {
+    x = 1,
+}
+
+local x
+t[x] = true
+]]
+
+TEST [[
+---@type table<string, string>
+local x
+
+---@type table<number, string>
+local y
+
+<!x!> = y
+]]
+
+TEST [[
+---@type table<string, string>
+local x
+
+---@type table<string, number>
+local y
+
+<!x!> = y
+]]
+
+TEST [[
+---@type table<string, string>
+local x
+
+---@type table<string, string>
+local y
+
+x = y
+]]
+
+TEST [[
+---@type { x: number, y: number }
+local t1
+
+---@type { x: number }
+local t2
+
+<!t1!> = t2
+]]
+
+TEST [[
+---@type { x: number, [integer]: number }
+local t1
+
+---@type { x: number }
+local t2
+
+<!t1!> = t2
+]]
+
+TEST [[
+local x
+
+if X then
+    x = 'A'
+elseif X then
+    x = 'B'
+else
+    x = 'C'
+end
+
+local y = x
+
+<!y!> = nil
+]]
+(function (diags)
+    local diag = diags[1]
+    assert(diag.message == [[
+已显式定义变量的类型为 `string` ，不能再将其类型转换为 `nil`。
+- `nil` 无法匹配 `string`
+- 类型 `nil` 无法匹配 `string`]])
+end)
+
+TEST [[
+---@type 'A'|'B'|'C'|'D'|'E'|'F'|'G'|'H'|'I'|'J'|'K'|'L'|'M'|'N'|'O'|'P'|'Q'|'R'|'S'|'T'|'U'|'V'|'W'|'X'|'Y'|'Z'
+local x
+
+<!x!> = nil
+]]
+(function (diags)
+    local diag = diags[1]
+    assert(diag.message == [[
+已显式定义变量的类型为 `'A'|'B'|'C'|'D'|'E'...(+21)` ，不能再将其类型转换为 `nil`。
+- `nil` 无法匹配 `'A'|'B'|'C'|'D'|'E'...(+21)`
+- `nil` 无法匹配 `'A'|'B'|'C'|'D'|'E'...(+21)` 中的任何子类
+- 类型 `nil` 无法匹配 `'Z'`
+- 类型 `nil` 无法匹配 `'Y'`
+- 类型 `nil` 无法匹配 `'X'`
+- 类型 `nil` 无法匹配 `'W'`
+- 类型 `nil` 无法匹配 `'V'`
+- 类型 `nil` 无法匹配 `'U'`
+- 类型 `nil` 无法匹配 `'T'`
+- 类型 `nil` 无法匹配 `'S'`
+- 类型 `nil` 无法匹配 `'R'`
+- 类型 `nil` 无法匹配 `'Q'`
+...(+13)
+- 类型 `nil` 无法匹配 `'C'`
+- 类型 `nil` 无法匹配 `'B'`
+- 类型 `nil` 无法匹配 `'A'`]])
+end)