- title: simple let
  template: |
    let
      ts: 100
      foo: 200
    in
      - ts + foo
      - ts - foo
      - ts * foo
  context: {}
  output: [300, -100, 20000]

- title: let with evaluated values
  template: |
    let
      thirty: 10 + 20
    in thirty + 5
  context: {}
  output: 35

- title: context overriding
  template: |
    let
      x: 20
    in x + y
  context: { x: 10, 'y': 1 }
  output: 21

- title: nested let
  template: |
    let
      x: 20
      "y": 10
    in
      let
        x: 30
      in
        x + y + z
  context: { x: 1, 'y': 2, z: 3 }
  output: 43
#
#- title: let with undefined properties
#  template: { $let: { x: 1, "y": 2 }, a: { $eval: "x + y" } }
#  context: {}
#  error:
#    type: ParseError
#    message: "value error: unknown field `a`, expected `$let` or `in`"

#- title: let array
#  template: { $let: [1, 2], in: { $eval: "1 + 2" } }
#  context: {}
#  error:
#    message: "context error: context value is not an object: List [Number(1), Number(2)]"

#- title: let null
#  template: { $let: null, in: { $eval: "1 + 2" } }
#  context: {}
#  error:
#    message: "context error: context value is not an object: Null"

#- title: checking name begin with number
#  context: {}
#  template:
#    {
#      $let: { ab: 100, bb: 200, 2b: 5 },
#      in: [{ $eval: "ab+bb" }, { $eval: "ab-bb" }, { $eval: "ab*bb" }],
#    }
#  error:
#    message: "context error: top level keys of context must follow /[a-zA-Z_][a-zA-Z0-9_]*: `2b`"

#- title: checking space in variable name
#  context: {}
#  template:
#    {
#      $let: { ab: 100, bb: 200, "a b": 10 },
#      in: [{ $eval: "ab+bb" }, { $eval: "ab-bb" }, { $eval: "ab*bb" }],
#    }
#  error:
#    message: "context error: top level keys of context must follow /[a-zA-Z_][a-zA-Z0-9_]*: `a b`"

#- title: checking special character in variable name
#  context: {}
#  template:
#    {
#      $let: { ab: 100, bb: 200, "a.b": 10 },
#      in: [{ $eval: "ab+bb" }, { $eval: "ab-bb" }, { $eval: "ab*bb" }],
#    }
#  error:
#    message: "context error: top level keys of context must follow /[a-zA-Z_][a-zA-Z0-9_]*: `a.b`"

#- title: checking integrity of operation $let with exact result
#  context: {}
#  template:
#    {
#      $let: { ts: 100, foo: 200 },
#      in: [{ $eval: "ts+foo" }, { $eval: "ts-foo" }, { $eval: "ts*foo" }],
#    }
#  output: [300, -100, 20000]

#- title:    checking $let and $reverse operator integrity
#  context:  {}
#  template: {$let: {x: [1, 2, 3]}, in: [$reverse: {$eval: "x"}]}
#  output:   [[ 3, 2, 1 ]]

#- title: checking $let with $if without else
#  context: { c: "itm" }
#  template:
#    { $let: { a: { $if: 'c == "item"', then: "value" } }, in: { a: "${a}" } }
#  error:
#    message: "missing context: a"

#- title: let with a value of $if-then-else
#  template:
#    {
#      $let:
#        { $if: something == 3, then: { a: 10, b: 20 }, else: { a: 20, b: 10 } },
#      in: { $eval: "a + b" },
#    }
#  context: { "something": 3 }
#  output: 30

#- title: let with a rendered key
#  template:
#    {
#      $let: { "first_${name}": 1, "second_${name}": 2 },
#      in: { $eval: "first_prize + second_prize" },
#    }
#  context: { name: "prize" }
#  output: 3

- title: let using values from the parent context
  template: |
    let
      b:
        a + 10
    in
      a + b
  context: { a: 5 }
  output: 20
#- title: let with a non-object rendered value (array)
#  template: { $let: { $eval: "[1, 2]" }, in: "uhoh" }
#  context: {}
#  error:
#    message: "context error: context value is not an object: List [Number(1), Number(2)]"

#- title: let with a non-object rendered value (string)
#  template: { $let: "${name}", in: "uhoh" }
#  context: { name: "fido" }
#  error:
#    message: 'context error: context value is not an object: String("fido")'

#- title: let with a non-object rendered value (boolean)
#  template: { $let: { $eval: "true" }, in: "uhoh" }
#  context: {}
#  error:
#    message: "context error: context value is not an object: true"

#- title:    fromNow with redefined `now`
#  context:  {}
#  template: {$let: {now: '2017-01-01T01:00:00.123Z'}, in: {$eval: "fromNow('1 day')"}}
#  output:   '2017-01-02T01:00:00.123Z'

#- title: defined with empty variable from a let expression
#  context: {}
#  template: {$let: {var: 10}, in: {$if: "defined('var')", then: 't', else: 'f'}}
#  output: t

#- title: $let with nested redefinitions of builtins
#  context: {}
#  template:
#    $let: {lowercase: {$eval: uppercase}}
#    in:
#      $let: {var: 10}
#      in:
#        $if: "defined('var')"
#        then: "${lowercase('t')}"  # lowercase should be redefined as uppercase
#        else: "${lowercase('f')}"
#  output: T

#- title: $let with nested redefinitions of builtins
#  context: {}
#  template:
#    $let: {fromNow: {$eval: uppercase}}
#    in:
#      $let: {var: 10}
#      in:
#        $if: "defined('var')"
#        then: "${fromNow('1 hour')}"
#        else: "f"
#  output: '1 HOUR'