output does not return the expected type 'bool' from CreateUIDefinition

**Issue:**
Got "output cosmosFreeApply does not return the expected type 'bool'" error when using test toolkit to check the template: https://docs.microsoft.com/en-us/azure/azure-resource-manager/templates/test-toolkit#test-parameters.

**Investigation:**
1. mainTemplate.json contains a bool parameter:
"parameters": {
"cosmosFreeApply": {
**"type": "bool",**
"defaultValue": true,
"metadata": {
"description": "Apply Free Level Discount."
}
}
3. createUIDefinition.json contains an output to the same parameter:
{
"$schema": "https://schema.management.azure.com/schemas/0.1.2-preview/CreateUIDefinition.MultiVm.json#",
"handler": "Microsoft.Azure.CreateUIDef",
"version": "0.1.2-preview",
"parameters": {
"basics": [],
"steps": [
{
"name": "otherSettings",
"label": "Details",
"elements": [
{
"name": "sectionCosmos",
"type": "Microsoft.Common.Section",
"label": "Cosmos DB",
"elements": [
{
"name": "cosmosTier",
"type": "Microsoft.Common.OptionsGroup",
"label": "Apply Free Plan",
"defaultValue": "No",
"toolTip": "Select whether to use Free Plan for Cosmos DB",
"constraints": {
"allowedValues": [
{
"label": "Yes",
"value": "[bool('true')]"
},
{
"label": "No",
"value": "[bool('false')]"
}
],
"required": true
}
}
]
}
]
}
],
"outputs": {
**"cosmosFreeApply": "[steps('otherSettings').sectionCosmos.cosmosTier]"**,
"location": "[location()]"
}
}
}

3.When using the Test-AzTemplate to check template, I got below error:
Validating customertest\createUiDefinition.json
JSONFiles Should Be Valid
[+] JSONFiles Should Be Valid (7 ms)

Allowed Values Should Actually Be Allowed
[+] Allowed Values Should Actually Be Allowed (21 ms)
Controls In Outputs Must Exist
[+] Controls In Outputs Must Exist (4 ms)
CreateUIDefinition Must Not Have Blanks
[+] CreateUIDefinition Must Not Have Blanks (5 ms)
CreateUIDefinition Should Have Schema
[+] CreateUIDefinition Should Have Schema (5 ms)
Credential Confirmation Should Not Be Hidden
[+] Credential Confirmation Should Not Be Hidden (16 ms)
Handler Must Be Correct
[+] Handler Must Be Correct (4 ms)
HideExisting Must Be Correctly Handled
[+] HideExisting Must Be Correctly Handled (15 ms)
Location Should Be In Outputs
[+] Location Should Be In Outputs (3 ms)
**CreateUIDefinition
[-] Outputs Must Be Present In Template Parameters (28 ms)
output cosmosFreeApply does not return the expected type 'bool'**

Parameters Without Default Must Exist In CreateUIDefinition
[+] Parameters Without Default Must Exist In CreateUIDefinition (4 ms)
Password Textboxes Must Be Used For Password Parameters
[+] Password Textboxes Must Be Used For Password Parameters (8 ms)
PasswordBoxes Must Have Min Length
[+] PasswordBoxes Must Have Min Length (8 ms)

.......

Pass : 47
Fail : 1
Total : 48

4.Navigate to the source script which is used to check output parameters: https://github.com/Azure/arm-ttk/blob/master/arm-ttk/testcases/CreateUIDefinition/Outputs-Must-Be-Present-In-Template-Parameters.test.ps1

It is evaluating two values: outputParameterType and firstOutputFunction:

```
if ($outputParameterType -eq $af.Key -and $firstOutputFunction -notin $af.Value) {
Write-Error "output $outputName does not return the expected type '$outputParameterType'" -ErrorId CreateUIDefinition.Output.Incorrect -TargetObject $parameterInfo.outputs
}
```

The $af.Key and $af.Value are retrieved from $AllowedFunctionInOutput as below:

```
$AllowedFunctionInOutput = $(@{
int = 'int', 'min', 'max', 'div', 'add', 'mod', 'mul', 'sub', 'copyIndex','length', 'coalesce'
bool = 'equals', 'less', 'lessOrEquals', 'greater', 'greaterOrEquals', 'and', 'or','not', 'true', 'false', 'contains','empty','coalesce','if'
})
)
```

Note the outputParameterType is generated from template parameter type (from mainTemplate) and firstOutputFunction is generated from the function name of the output (from CreateUiDefinition):

```
$outputParameterType = $TemplateObject.parameters.$outputName.type
$firstOutputFunction = $output.Value | ? -Extract | Select-Object -ExpandProperty FunctionName
```

The outputParameterType is bool which is expected, however, the firstOutputFunction in this case gets a value as steps which is not in above $AllowedFunctionInOutput values {'equals', 'less', 'lessOrEquals', 'greater', 'greaterOrEquals', 'and', 'or','not', 'true', 'false', 'contains','empty','coalesce','if'}. Therefore, it results in an error.

```
"outputs": {
"cosmosFreeApply": "[steps('otherSettings').sectionCosmos.cosmosTier]",
"location": "[location()]"
}
```

It looks like logic is not suitable in CreateUiDefinition because this file is made up of different elements instead of normal function used in ARM template.

May I ask if you could help to look at and fix the issue?

Start with arm-ttk/testcases/CreateUIDefinition/Outputs-Must-Be-Present-In-Template-Parameters.test.ps1 and trace how outputParameterType and firstOutputFunction are extracted for createUiDefinition.json. Reproduce the failure with Test-AzTemplate using the reported mainTemplate.json and createUiDefinition.json; done means the valid bool output passes without breaking the existing output checks.

Written by the indexing model from the issue text.