Tests multiple different cases where a resource, module, or property condition evaluates to false, and therefore should never evaluate in the first place.

bicepconfig.json

{
  // See https://aka.ms/bicep/config for more information on Bicep configuration options
  // Press CTRL+SPACE/CMD+SPACE at any location to see Intellisense suggestions
  "analyzers": {
    "core": {
      "rules": {
        "no-unused-params": {
          "level": "warning"
        }
      }
    }
  },
  "experimentalFeaturesEnabled": {
    // "resourceDerivedTypes": true,
    // "symbolicNameCodegen": true, //enable or disable according to test
    "optionalModuleNames": true 
    
  }
}

main.bicep

// *** TEST 1 ***
// preflight failure for condition false resource, payload is invalid according to RP-specific preflight
resource falseResource 'Microsoft.Storage/storageAccounts@2023-01-01' = if(false) {
  name: 'abc123'
  location: resourceGroup().location
  kind: 'StorageV2'
  sku: {
    name: 'Standard_LRS'
  }
}

// // result without symbolic name: success
// // result with symbolic name: success




// // *** TEST 2 ***
// // parameter reference causes failure, but params shouldn't even be evaluated
// // seems to be the issue described in both:
// // * https://github.com/Azure/bicep/issues/2371
// // * https://github.com/Azure/bicep/issues/3990
module falseModule 'mod.bicep' = if(false) {
  params: {
    test: falseResource.properties.primaryEndpoints.blob
  }
}

// // result without symbolic name: !! FAILURE !!
// // result with symbolic name: success


// // *** TEST 3 ***
// // https://github.com/Azure/bicep/issues/3750
// // ternary where first operand is false, so the second operand should never evaluate
module trueModuleNullReferenceShouldEvaluate 'mod.bicep' = {
  params: {
    test: false ? falseResource.properties.primaryEndpoints.blob : ''
  }
}

// // result without symbolic name: !!! FAILURE !!!
// // result with symbolic name: success


// // *** TEST 4 ***
// // https://github.com/Azure/bicep/issues/3750
// // THIS TEST SHOULD FAIL
// ternary where first operand is true, so second operand SHOULD evaluate and fail
module trueModuleNullReferenceShouldNotEvaluate 'mod.bicep' = {
  params: {
    test: true ? falseResource.properties.primaryEndpoints.blob : ''
  }
}

// // result without symbolic name: !!! FAILURE !!!
// // result with symbolic name: !!! FAILURE !!!



// *** TEST 5 ***
// foo expression evaluates to false based on parameter value, payload is invalid according to Deployments
param foo string = ''

resource bar 'Microsoft.Storage/storageAccounts@2023-01-01' = if (foo != '') {
  name: foo
  location: resourceGroup().location
  kind: 'StorageV2'
  sku: {
    name: 'Standard_LRS'
  }
}

// result without symbolic name: !!! FAILURE !!!
// result with symbolic name: !!! FAILURE !!!

// sidenote: with condiiton true, it passed storage preflight if the properties were missing

The other thing I've seen some complaints about is the scenario like this one:

param foo string = ''

resource bar 'Microsoft.Storage/storageAccounts@2023-01-01' = if (foo != '') {
  name: foo
}

It's not a huge deal to work around, but it does force awkward code like this:

param foo string = ''

resource bar 'Microsoft.Storage/storageAccounts@2023-01-01' = if (foo != '') {
  name: foo != '' ? foo : 'NOTUSED'
}

Just updated. This example succeeds in both cases.

Fixed adding the new case, which appears to be unresolved for symbolic names too.

Adding internal ADO work item for tracking: https://msazure.visualstudio.com/One/_workitems/edit/27778828

Fixing this item should also resolve: Azure/bicep#13937