Handle empty strings in s3 cors settings.

[jmcarp]

[Fixes #4258]

Changes proposed in this pull request:

• Check that interface{} can be cast to string in cors settings
• Add regression test

Output from acceptance testing:

± time TF_ACC=1 go test ./... -run TestAccAWSS3Bucket_Cors -v
?       github.com/terraform-providers/terraform-provider-aws   [no test files]
=== RUN   TestAccAWSS3Bucket_Cors
--- PASS: TestAccAWSS3Bucket_Cors (83.88s)
PASS
ok      github.com/terraform-providers/terraform-provider-aws/aws       83.932s

[bflad]

Thanks for this @jmcarp -- looks correct 🚀

Test failures unrelated.

=== RUN   TestAccAWSS3BucketObject_withContentCharacteristics
--- PASS: TestAccAWSS3BucketObject_withContentCharacteristics (10.47s)
=== RUN   TestAccAWSS3BucketObject_source
--- PASS: TestAccAWSS3BucketObject_source (10.76s)
=== RUN   TestAccAWSS3BucketObject_contentBase64
--- PASS: TestAccAWSS3BucketObject_contentBase64 (11.17s)
=== RUN   TestAccAWSS3BucketObject_sse
--- PASS: TestAccAWSS3BucketObject_sse (12.12s)
=== RUN   TestAccAWSS3BucketNotification_withoutFilter
--- PASS: TestAccAWSS3BucketNotification_withoutFilter (13.29s)
=== RUN   TestAccAWSS3BucketObject_content
--- PASS: TestAccAWSS3BucketObject_content (20.48s)
=== RUN   TestAccAWSS3Bucket_importWithPolicy
--- PASS: TestAccAWSS3Bucket_importWithPolicy (26.59s)
=== RUN   TestAccAWSS3BucketObject_kms
--- PASS: TestAccAWSS3BucketObject_kms (31.00s)
=== RUN   TestAccAWSS3BucketMetric_basic
--- PASS: TestAccAWSS3BucketMetric_basic (31.58s)
=== RUN   TestAccAWSS3Bucket_namePrefix
--- PASS: TestAccAWSS3Bucket_namePrefix (11.85s)
=== RUN   TestAccAWSS3Bucket_importBasic
--- PASS: TestAccAWSS3Bucket_importBasic (36.55s)
=== RUN   TestAccAWSS3BucketObject_acl
--- PASS: TestAccAWSS3BucketObject_acl (36.81s)
=== RUN   TestAccAWSS3BucketMetric_WithFilterMultipleTags
--- PASS: TestAccAWSS3BucketMetric_WithFilterMultipleTags (37.34s)
=== RUN   TestAccAWSS3BucketMetric_WithFilterPrefixAndMultipleTags
--- PASS: TestAccAWSS3BucketMetric_WithFilterPrefixAndMultipleTags (39.37s)
=== RUN   TestAccAWSS3BucketObject_tags
--- PASS: TestAccAWSS3BucketObject_tags (30.35s)
=== RUN   TestAccAWSS3BucketObject_updatesWithVersioning
--- PASS: TestAccAWSS3BucketObject_updatesWithVersioning (45.58s)
=== RUN   TestAccAWSS3BucketObject_updates
--- PASS: TestAccAWSS3BucketObject_updates (50.61s)
=== RUN   TestAccAWSS3BucketMetric_WithFilterPrefixAndSingleTag
--- PASS: TestAccAWSS3BucketMetric_WithFilterPrefixAndSingleTag (51.20s)
=== RUN   TestAccAWSS3BucketMetric_WithFilterSingleTag
--- PASS: TestAccAWSS3BucketMetric_WithFilterSingleTag (54.32s)
=== RUN   TestAccAWSS3Bucket_region
--- PASS: TestAccAWSS3Bucket_region (35.40s)
=== RUN   TestAccAWSS3Bucket_enableDefaultEncryption_whenAES256IsUsed
--- PASS: TestAccAWSS3Bucket_enableDefaultEncryption_whenAES256IsUsed (20.71s)
=== RUN   TestAccAWSS3Bucket_RequestPayer
--- PASS: TestAccAWSS3Bucket_RequestPayer (44.69s)
=== RUN   TestAccAWSS3Bucket_Logging
--- FAIL: TestAccAWSS3Bucket_Logging (11.48s)
=== RUN   TestAccAWSS3Bucket_enableDefaultEncryption_whenTypical
--- PASS: TestAccAWSS3Bucket_enableDefaultEncryption_whenTypical (48.60s)
=== RUN   TestAccAWSS3Bucket_UpdateAcl
--- PASS: TestAccAWSS3Bucket_UpdateAcl (60.39s)
=== RUN   TestAccAWSS3BucketObject_storageClass
--- PASS: TestAccAWSS3BucketObject_storageClass (90.96s)
=== RUN   TestAccAWSS3Bucket_Versioning
--- FAIL: TestAccAWSS3Bucket_Versioning (35.07s)
=== RUN   TestAccAWSS3Bucket_WebsiteRedirect
--- PASS: TestAccAWSS3Bucket_WebsiteRedirect (64.09s)
=== RUN   TestAccAWSS3BucketNotification_basic
--- PASS: TestAccAWSS3BucketNotification_basic (104.03s)
=== RUN   TestAccAWSS3BucketPolicy_policyUpdate
--- PASS: TestAccAWSS3BucketPolicy_policyUpdate (93.60s)
=== RUN   TestAccAWSS3Bucket_WebsiteRoutingRules
--- FAIL: TestAccAWSS3Bucket_WebsiteRoutingRules (65.35s)
=== RUN   TestAccAWSS3Bucket_Website_Simple
--- PASS: TestAccAWSS3Bucket_Website_Simple (69.91s)
=== RUN   TestAccAWSS3Bucket_acceleration
--- PASS: TestAccAWSS3Bucket_acceleration (78.07s)
=== RUN   TestAccAWSS3Bucket_LifecycleExpireMarkerOnly
--- PASS: TestAccAWSS3Bucket_LifecycleExpireMarkerOnly (20.31s)
=== RUN   TestAccAWSS3Bucket_Policy
--- PASS: TestAccAWSS3Bucket_Policy (79.97s)
=== RUN   TestAccAWSS3Bucket_basic
--- PASS: TestAccAWSS3Bucket_basic (105.58s)
=== RUN   TestAccAWSS3Bucket_disableDefaultEncryption_whenDefaultEncryptionIsEnabled
--- PASS: TestAccAWSS3Bucket_disableDefaultEncryption_whenDefaultEncryptionIsEnabled (71.82s)
=== RUN   TestAccAWSS3Bucket_generatedName
--- PASS: TestAccAWSS3Bucket_generatedName (96.95s)
=== RUN   TestAccAWSS3Bucket_Lifecycle
--- PASS: TestAccAWSS3Bucket_Lifecycle (35.01s)
=== RUN   TestAccAWSS3Bucket_Cors
--- PASS: TestAccAWSS3Bucket_Cors (56.86s)
=== RUN   TestAccAWSS3Bucket_ReplicationExpectVersioningValidationError
--- PASS: TestAccAWSS3Bucket_ReplicationExpectVersioningValidationError (34.88s)
=== RUN   TestAccAWSS3Bucket_shouldFailNotFound
--- PASS: TestAccAWSS3Bucket_shouldFailNotFound (97.01s)
=== RUN   TestAccAWSS3Bucket_ReplicationWithoutStorageClass
--- PASS: TestAccAWSS3Bucket_ReplicationWithoutStorageClass (51.20s)
=== RUN   TestAccAWSS3BucketMetric_WithFilterPrefix
--- PASS: TestAccAWSS3BucketMetric_WithFilterPrefix (169.97s)
=== RUN   TestAccAWSS3BucketNotification_importBasic
--- PASS: TestAccAWSS3BucketNotification_importBasic (173.99s)
=== RUN   TestAccAWSS3BucketPolicy_basic
--- PASS: TestAccAWSS3BucketPolicy_basic (184.38s)
=== RUN   TestAccAWSS3Bucket_Replication
--- PASS: TestAccAWSS3Bucket_Replication (120.93s)

[bflad]

This has been released in version 1.18.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!