Add @validate() decorator for custom validation

[jeskew]

Resolves #2922 and resolves #16988

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 17043723403)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 17043723403

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 17043723403"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 17043723403

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 17043723403"

[github-actions]

Dotnet Test Results

    90 files   -     45      90 suites   - 45   37m 42s ⏱️ - 20m 5s
12 278 tests  -      9  12 278 ✅  -      9  0 💤 ±0  0 ❌ ±0 
28 311 runs   - 14 142  28 311 ✅  - 14 142  0 💤 ±0  0 ❌ ±0 

Results for commit 648354d. ± Comparison against base commit d5a9da2.

This pull request removes 1905 and adds 651 tests. Note that renamed tests count towards both.

		nestedProp1: 1
		nestedProp2: 2
		prop1: true
		prop2: false
	1
	2
	\$'")
	prop1: true
	prop2: false
…

Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000
�ӽ\u000e�0\u0010\u0000��>E�\u0003@\u000b�VL�]L\|�
g�\u0008\u0012�	���-�q���cb��C�^�;?��v�:ú�%�2��ؘ%����p�\u0008Wo�0\u0005v%�\u001d��\u001e���ږ2�Y?(\Sm�\u0002\u0013�\u0000 T�R�
�\u0010\�l,\u001d��Vڜ��̰�/ͭ�ҋ�����\u000c���tO�m�Y$\u0008\u0007\u0006LF �\u0013f�F���e&�|�\u001f�;��V�\u001a�vX\u001c��6���
>���q\u001cǙ�\u000bQ�2�\u0000\u000c\u0000\u0000,"Value cannot be null. (Parameter 'source')")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000
��K\u000e�0\u0010\u0006�=\u0005'(3-ӑ\u0005{�^�Q\u0012\u001f�\u0018\u001e��xw���\u0005�
�����L:m�W�{��r{̫Z\u001aJM,���3I2�>@B��\u0002\u0002��\u0016"�g�dD[7��,��\u000fR��6�"ϐ�Hq�,I�\u0001�7�v��at��)k�Օ����tCC1հ�A�Q����+���\u0000%���hJ�_\u0000�Z��/��?�����\u0004A\u0010\u0004�\u001a�9G��\u0000\u000c\u0000\u0000,"The path: index.json was not found in artifact contents")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000
��O\u000b� \u0014\u0000p�}��\u000f�t�i\u0006;\u0004\u001dZ�
��!Mh�Vl\u000b\u0006}��!�ltٟ ��\u0007�\u0003��\u0013{{U��JtQb\u000e�{\u0018��\u0018����\u0006e\u0002Q�F\u0010\u0011`f�ԽW��QV�0����\u000f�玪�L�T\u0000�/�\u0010\u0018d ̘�ع+F�sW�%L�D��Z��&=�J���V���
wE����\u000cQ @x\u0000\u000c("\u001c\u00187�?JO�y�?�(>.���9�bw�\u001fx�,˲��\u0000~C��\u0000\u000c\u0000\u0000,"'7' is an invalid end of a number. Expected a delimiter. Path: $.INVALID_JSON | LineNumber: 0 | BytePositionInLine: 20.")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000\u0003�ӽ\u000e�0\u0010\u0007��>\u0005OP�Z�Z\u0007vG_�Q\u0012?B1\u0002������\u0001�`b�c/�����t�M��ŵ�Z�N��\u001a\u0004�e��=$\u0014h^@���\u0008�t�o2��\u001bw
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�����Y2����?�� ��(Z�\u0013\u0015>��\u0000\u000c\u0000\u0000,"The path: index.json was not found in artifact contents")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000\u0003��A\u000b�0\u0014\u0000���\u0015�\u000f�o�6
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' �}p�'��?���\u001d'��&^\u001e��mb�-���]�a\u0018�1�'���\u001f\u0000\u000c\u0000\u0000,"'7' is an invalid end of a number. Expected a delimiter. Path: $.INVALID_JSON | LineNumber: 0 | BytePositionInLine: 20.")
Bicep.Core.IntegrationTests.AzTypesViaRegistryTests ‑ Bicep_compiler_handles_corrupted_extension_package_gracefully (\u001f�\u0008\u0000\u0000\u0000\u0000\u0000\u0000\u0003��K\u000e�0\u0010\u0006�=E�\u0001jK�\u0016Lػ1q�\u0001*�\u0011#H\u0000\u0013\u0012��-\u000b�\u0006ↇ����$3}�l�7�\u0016M�Uͤ�䚑�qK\u0005A�zG\u0004�\u0008��	�\u0000����O��^7������\u0007�!5M�c,쥃�C\u00151%C
R��^2�'"Z��\u001cgE�-�Է�+χʗ>�3��~�����.\u0003"�\u0003W�~\u001b \\u0001H��Y2����P�P`[b�`�������'s���l��8�t^�Ĉ/\u0000\u000c\u0000\u0000,"Value cannot be null. (Parameter 'source')")
Bicep.Core.IntegrationTests.DirectResourceCollectionTests ‑ DirectResourceCollectionAccess_NotAllowedWithinLoops ("output loopOutput array = [for i in range(0, 2): {
  prop: map(containerWorkers, (w) => w.properties.ipAddress.ip)
}]")
Bicep.Core.IntegrationTests.DirectResourceCollectionTests ‑ DirectResourceCollectionAccess_NotAllowedWithinLoops ("resource propertyLoop 'Microsoft.ContainerInstance/containerGroups@2022-09-01' = {
  name: 'gh9440-loop'
  location: 'westus'
  properties: {
    containers: [for i in range(0, 2): {
      name: 'gh9440-w1c-${i}'
      properties: {
        command: [
          'echo "${join(map(containerWorkers, (w) => w.properties.ipAddress.ip), ',')}"'
        ]
      }
    }]
  }
}")
Bicep.Core.IntegrationTests.DirectResourceCollectionTests ‑ DirectResourceCollectionAccess_NotAllowedWithinLoops ("var loopVar = [for i in range(0, 2): {
  prop: map(containerWorkers, (w) => w.properties.ipAddress.ip)
}]")
Bicep.Core.IntegrationTests.Emit.ParamsFileWriterTests ‑ Params_file_with_no_errors_should_compile_correctly ("
using 'main.bicep'

// involves all syntax
param myParam = {
  arr: [
    {
      a : 'b'
    }
    {
      c : true
    }
  ]
  name: 'complex object!'
  priority: 3
  val: null
  obj: {
      a: 'b'
      c: [
          'd'
           1
      ]
  }
}","
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "myParam": {
      "value": {
        "arr" : [
          {
            "a" : "b"
          },
          {
            "c" : true
          }
        ],
        "name" : "complex object!",
        "priority" : 3,
        "val" : null,
        "obj" : {
          "a" : "b",
          "c" : [
            "d",
            1
          ]
        }
      }
    }
  }
}","
param myParam object
")
…

♻️ This comment has been updated with latest results.

[jeskew]

User defined constraints are added in this PR as a runtime-only feature; they will be checked by the ARM engine when the template is deployed, but they are not checked by Bicep at compile time. This was done because we don't have a good way to eval a lambda, and adding such a mechanism (which would also make type inference on map, filter, reduce, etc. better) is a big undertaking. I'm OK with this limitation since the @validate() decorator added by this PR requires a feature flag to use.

[jeskew]

A second limitation is that while user-defined constraints in ARM support multiple predicates, I couldn't find a way to define a decorator that:

• Has one required parameter (a lambda predicate)
• Has an optional string parameter
• Will accept additional lambda + string pairs

The ARM function will accept a single argument or an even number of arguments, where the even numbered arguments (0-indexed) must be lambdas and the odd numbered arguments must be strings. We don't currently support overloads for decorator functions, which thwarted my plan to fake this by defining three overloads:

• validate(predicate: lambda)
• validate(predicate: lambda, errorMessage: string)
• validate(predicate: lambda, errorMessage: string, secondPredicate: lambda, secondPredicate: string)

and then just adding more overloads in the future as requested.

This limitation also seems fine in an experimental feature.

[shenglol]

Should this be >?