Terraform Test
HashiCorpOfficialPublished by HashiCorp
- Skill
- Tool integration
- Cloud and DevOps
- MPL-2.0
- No issues found
AutoGineer summary
Written by AutoGineer from the skill’s own files, not by the author
This skill provides a structured approach to using Terraform's native testing framework. It covers the creation of .tftest.hcl files, the use of run and assert blocks for validation, and strategies for both plan-mode unit testing and apply-mode integration testing. It also details how to utilize mock providers to simulate infrastructure without requiring cloud credentials, and how to integrate these tests into CI/CD pipelines.
What it does
- Defines test scenarios using run and assert blocks within .tftest.hcl files.
- Supports both plan-mode unit tests and apply-mode integration tests.
- Enables mocking of providers and data sources for faster, credential-free testing.
- Provides patterns for validating outputs, resource counts, and conditional logic.
- Offers guidance on CI/CD integration for automated testing workflows.
- Explains state isolation and cleanup procedures for infrastructure tests.
When to use it
- When you need to validate that configuration changes do not introduce breaking changes.
- When you want to implement unit testing for Terraform modules without deploying real resources.
- When you need to perform integration testing to verify infrastructure behavior in a live environment.
- When you need to mock external dependencies to speed up test execution.
- When setting up automated testing pipelines in GitHub Actions or GitLab CI.
Advantages
- Native integration with Terraform CLI.
- Supports rapid feedback loops via plan-mode testing.
- Reduces risk by validating infrastructure logic before deployment.
- Simplifies testing through built-in mocking capabilities.
- Enables consistent testing standards across team modules.
Usage examples
- “How do I write a basic plan-mode test for my Terraform module?”
- The agent will provide a template for a .tftest.hcl file using a run block with command = plan and an assert block to verify specific resource attributes.
- “How can I test my infrastructure without needing AWS credentials?”
- The agent will explain how to use the mock_provider block to simulate provider behavior, allowing you to run tests in plan mode without real cloud access.
- “What is the best way to organize my test files?”
- The agent will recommend a directory structure using *_unit_test.tftest.hcl for plan-mode tests and *_integration_test.tftest.hcl for apply-mode tests.
- “How do I run only my unit tests in a CI pipeline?”
- The agent will provide the command terraform test -filter=unit_test and show how to map this to your CI/CD configuration files.
Install
Download the skill as a ZIP:
https://mp-staging.autogineer.com/agent-skills/hashicorp/terraform-test/downloadUnzip it into the cross-client skills folder of your project:
mkdir -p .agents/skills && unzip terraform-test.zip -d .agents/skills
Documentation by HashiCorp
Terraform Test
Terraform's built-in testing framework validates that configuration updates don't introduce breaking changes. Tests run against temporary resources, protecting existing infrastructure and state files.
Reference Files
references/MOCK_PROVIDERS.md— Mock provider syntax, common defaults, when to use mocks (Terraform 1.7.0+ only — skip if the user's version is below 1.7)references/CI_CD.md— GitHub Actions and GitLab CI pipeline examplesreferences/EXAMPLES.md— Complete example test suite (unit, integration, and mock tests for a VPC module)
Read the relevant reference file when the user asks about mocking, CI/CD integration, or wants a full example.
Core Concepts
Test file (
.tftest.hcl/.tftest.json): Containsrunblocks that validate your configurationRun block: A single test scenario with optional variables, providers, and assertions
Assert block: Conditions that must be true for the test to pass
Mock provider: Simulates provider behavior without real infrastructure (Terraform 1.7.0+)
Test modes:
apply(default, creates real resources) orplan(validates logic only)
File Structure
my-module/
├── main.tf
├── variables.tf
├── outputs.tf
└── tests/
├── defaults_unit_test.tftest.hcl # plan mode — fast, no resources
├── validation_unit_test.tftest.hcl # plan mode
└── full_stack_integration_test.tftest.hcl # apply mode — creates real resourcesUse *_unit_test.tftest.hcl for plan-mode tests and *_integration_test.tftest.hcl for apply-mode tests so they can be filtered separately in CI.
Test File Structure
# Optional: test-wide settings
test {
parallel = true # Enable parallel execution for all run blocks (default: false)
}
# Optional: file-level variables (highest precedence, override all other sources)
variables {
aws_region = "us-west-2"
instance_type = "t2.micro"
}
# Optional: provider configuration
provider "aws" {
region = var.aws_region
}
# Required: at least one run block
run "test_default_configuration" {
command = plan
assert {
condition = aws_instance.example.instance_type == "t2.micro"
error_message = "Instance type should be t2.micro by default"
}
}Run Block
run "test_name" {
command = plan # or apply (default)
parallel = true # optional, since v1.9.0
# Override file-level variables
variables {
instance_type = "t3.large"
}
# Reference a specific module
module {
source = "./modules/vpc" # local or registry only (not git/http)
version = "5.0.0" # registry modules only
}
# Control state isolation
state_key = "shared_state" # since v1.9.0
# Plan behavior
plan_options {
mode = refresh-only # or normal (default)
refresh = true
replace = [aws_instance.example]
target = [aws_instance.example]
}
# Assertions
assert {
condition = aws_instance.example.id != ""
error_message = "Instance should have a valid ID"
}
# Expected failures (test passes if these fail)
expect_failures = [
var.instance_count
]
}Common Test Patterns
Validate outputs
run "test_outputs" {
command = plan
assert {
condition = output.vpc_id != null
error_message = "VPC ID output must be defined"
}
assert {
condition = can(regex("^vpc-", output.vpc_id))
error_message = "VPC ID should start with 'vpc-'"
}
}Conditional resources
run "test_nat_gateway_disabled" {
command = plan
variables {
create_nat_gateway = false
}
assert {
condition = length(aws_nat_gateway.main) == 0
error_message = "NAT gateway should not be created when disabled"
}
}Resource counts
run "test_resource_count" {
command = plan
variables {
instance_count = 3
}
assert {
condition = length(aws_instance.workers) == 3
error_message = "Should create exactly 3 worker instances"
}
}Tags
run "test_resource_tags" {
command = plan
variables {
common_tags = {
Environment = "production"
ManagedBy = "Terraform"
}
}
assert {
condition = aws_instance.example.tags["Environment"] == "production"
error_message = "Environment tag should be set correctly"
}
assert {
condition = aws_instance.example.tags["ManagedBy"] == "Terraform"
error_message = "ManagedBy tag should be set correctly"
}
}Data sources
run "test_data_source_lookup" {
command = plan
assert {
condition = data.aws_ami.ubuntu.id != ""
error_message = "Should find a valid Ubuntu AMI"
}
assert {
condition = can(regex("^ami-", data.aws_ami.ubuntu.id))
error_message = "AMI ID should be in correct format"
}
}Validation rules
run "test_invalid_environment" {
command = plan
variables {
environment = "invalid"
}
expect_failures = [
var.environment
]
}Sequential tests with dependencies
run "setup_vpc" {
command = apply
assert {
condition = output.vpc_id != ""
error_message = "VPC should be created"
}
}
run "test_subnet_in_vpc" {
command = plan
variables {
vpc_id = run.setup_vpc.vpc_id
}
assert {
condition = aws_subnet.example.vpc_id == run.setup_vpc.vpc_id
error_message = "Subnet should be in the VPC from setup_vpc"
}
}Plan options (refresh-only, targeted)
run "test_refresh_only" {
command = plan
plan_options {
mode = refresh-only
}
assert {
condition = aws_instance.example.tags["Environment"] == "production"
error_message = "Tags should be refreshed correctly"
}
}
run "test_specific_resource" {
command = plan
plan_options {
target = [aws_instance.example]
}
assert {
condition = aws_instance.example.instance_type == "t2.micro"
error_message = "Targeted resource should be planned"
}
}Parallel modules
run "test_networking_module" {
command = plan
parallel = true
module {
source = "./modules/networking"
}
assert {
condition = output.vpc_id != ""
error_message = "VPC should be created"
}
}
run "test_compute_module" {
command = plan
parallel = true
module {
source = "./modules/compute"
}
assert {
condition = output.instance_id != ""
error_message = "Instance should be created"
}
}State key sharing
run "create_foundation" {
command = apply
state_key = "foundation"
assert {
condition = aws_vpc.main.id != ""
error_message = "Foundation VPC should be created"
}
}
run "create_application" {
command = apply
state_key = "foundation"
variables {
vpc_id = run.create_foundation.vpc_id
}
assert {
condition = aws_instance.app.vpc_id == run.create_foundation.vpc_id
error_message = "Application should use foundation VPC"
}
}Cleanup ordering (S3 objects before bucket)
run "create_bucket" {
command = apply
assert {
condition = aws_s3_bucket.example.id != ""
error_message = "Bucket should be created"
}
}
run "add_objects" {
command = apply
assert {
condition = length(aws_s3_object.files) > 0
error_message = "Objects should be added"
}
}
# Cleanup destroys in reverse: objects first, then bucketMultiple aliased providers
provider "aws" {
alias = "primary"
region = "us-west-2"
}
provider "aws" {
alias = "secondary"
region = "us-east-1"
}
run "test_with_specific_provider" {
command = plan
providers = {
aws = provider.aws.secondary
}
assert {
condition = aws_instance.example.availability_zone == "us-east-1a"
error_message = "Instance should be in us-east-1 region"
}
}Complex conditions
assert {
condition = alltrue([
for subnet in aws_subnet.private :
can(regex("^10\\.0\\.", subnet.cidr_block))
])
error_message = "All private subnets should use 10.0.0.0/8 CIDR range"
}Cleanup
Resources are destroyed in reverse run block order after test completion. This matters for dependencies (e.g., S3 objects before bucket). Use terraform test -no-cleanup to skip cleanup for debugging.
Running Tests
terraform test # all tests
terraform test tests/defaults.tftest.hcl # specific file
terraform test -filter=test_vpc_configuration # by run block name
terraform test -test-directory=integration-tests # custom directory
terraform test -verbose # detailed output
terraform test -no-cleanup # skip resource cleanupBest Practices
Naming:
*_unit_test.tftest.hclfor plan mode,*_integration_test.tftest.hclfor apply modeTest naming: Use descriptive run block names that explain the scenario being tested
Default to plan: Use
command = planunless you need to test real resource behaviorUse mocks for external dependencies — faster and no credentials needed (see
references/MOCK_PROVIDERS.md)Error messages: Make them specific enough to diagnose failures without running the test again
Negative tests: Use
expect_failuresto verify validation rules reject bad inputsVariable coverage: Test different variable combinations to validate all code paths — test variables have the highest precedence and override all other sources
Module sources: Test files only support local paths and registry modules — not git or HTTP URLs
Parallel execution: Use
parallel = truefor independent tests with different state filesCleanup: Integration tests destroy resources in reverse run block order automatically; use
-no-cleanupfor debuggingCI/CD: Run unit tests on every PR, integration tests on merge (see
references/CI_CD.md)
Troubleshooting
| Issue | Solution |
|---|---|
| Assertion failures | Use -verbose to see actual vs expected values |
| Missing credentials | Use mock providers for unit tests |
| Unsupported module source | Convert git/HTTP sources to local modules |
| Tests interfering | Use state_key or separate modules for isolation |
| Slow tests | Use command = plan and mocks; run integration tests separately |
References
Files
- ATTRIBUTION.mdAdded by AutoGineer896 B
- LICENSELicence file added by AutoGineer16.3 KiB
- SKILL.md10.9 KiB
- references/CI_CD.md1.9 KiB
- references/EXAMPLES.md6.5 KiB
- references/MOCK_PROVIDERS.md4.4 KiB
LICENSE
Mozilla Public License Version 2.0
==================================
1. Definitions
--------------
1.1. "Contributor"
means each individual or legal entity that creates, contributes to
the creation of, or owns Covered Software.
1.2. "Contributor Version"
means the combination of the Contributions of others (if any) used
by a Contributor and that particular Contributor's Contribution.
1.3. "Contribution"
means Covered Software of a particular Contributor.
1.4. "Covered Software"
means Source Code Form to which the initial Contributor has attached
the notice in Exhibit A, the Executable Form of such Source Code
Form, and Modifications of such Source Code Form, in each case
including portions thereof.
1.5. "Incompatible With Secondary Licenses"
means
(a) that the initial Contributor has attached the notice described
in Exhibit B to the Covered Software; or
(b) that the Covered Software was made available under the terms of
version 1.1 or earlier of the License, but not also under the
terms of a Secondary License.
1.6. "Executable Form"
means any form of the work other than Source Code Form.
1.7. "Larger Work"
means a work that combines Covered Software with other material, in
a separate file or files, that is not Covered Software.
1.8. "License"
means this document.
1.9. "Licensable"
means having the right to grant, to the maximum extent possible,
whether at the time of the initial grant or subsequently, any and
all of the rights conveyed by this License.
1.10. "Modifications"
means any of the following:
(a) any file in Source Code Form that results from an addition to,
deletion from, or modification of the contents of Covered
Software; or
(b) any new file in Source Code Form that contains any Covered
Software.
1.11. "Patent Claims" of a Contributor
means any patent claim(s), including without limitation, method,
process, and apparatus claims, in any patent Licensable by such
Contributor that would be infringed, but for the grant of the
License, by the making, using, selling, offering for sale, having
made, import, or transfer of either its Contributions or its
Contributor Version.
1.12. "Secondary License"
means either the GNU General Public License, Version 2.0, the GNU
Lesser General Public License, Version 2.1, the GNU Affero General
Public License, Version 3.0, or any later versions of those
licenses.
1.13. "Source Code Form"
means the form of the work preferred for making modifications.
1.14. "You" (or "Your")
means an individual or a legal entity exercising rights under this
License. For legal entities, "You" includes any entity that
controls, is controlled by, or is under common control with You. For
purposes of this definition, "control" means (a) the power, direct
or indirect, to cause the direction or management of such entity,
whether by contract or otherwise, or (b) ownership of more than
fifty percent (50%) of the outstanding shares or beneficial
ownership of such entity.
2. License Grants and Conditions
--------------------------------
2.1. Grants
Each Contributor hereby grants You a world-wide, royalty-free,
non-exclusive license:
(a) under intellectual property rights (other than patent or trademark)
Licensable by such Contributor to use, reproduce, make available,
modify, display, perform, distribute, and otherwise exploit its
Contributions, either on an unmodified basis, with Modifications, or
as part of a Larger Work; and
(b) under Patent Claims of such Contributor to make, use, sell, offer
for sale, have made, import, and otherwise transfer either its
Contributions or its Contributor Version.
2.2. Effective Date
The licenses granted in Section 2.1 with respect to any Contribution
become effective for each Contribution on the date the Contributor first
distributes such Contribution.
2.3. Limitations on Grant Scope
The licenses granted in this Section 2 are the only rights granted under
this License. No additional rights or licenses will be implied from the
distribution or licensing of Covered Software under this License.
Notwithstanding Section 2.1(b) above, no patent license is granted by a
Contributor:
(a) for any code that a Contributor has removed from Covered Software;
or
(b) for infringements caused by: (i) Your and any other third party's
modifications of Covered Software, or (ii) the combination of its
Contributions with other software (except as part of its Contributor
Version); or
(c) under Patent Claims infringed by Covered Software in the absence of
its Contributions.
This License does not grant any rights in the trademarks, service marks,
or logos of any Contributor (except as may be necessary to comply with
the notice requirements in Section 3.4).
2.4. Subsequent Licenses
No Contributor makes additional grants as a result of Your choice to
distribute the Covered Software under a subsequent version of this
License (see Section 10.2) or under the terms of a Secondary License (if
permitted under the terms of Section 3.3).
2.5. Representation
Each Contributor represents that the Contributor believes its
Contributions are its original creation(s) or it has sufficient rights
to grant the rights to its Contributions conveyed by this License.
2.6. Fair Use
This License is not intended to limit any rights You have under
applicable copyright doctrines of fair use, fair dealing, or other
equivalents.
2.7. Conditions
Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
in Section 2.1.
3. Responsibilities
-------------------
3.1. Distribution of Source Form
All distribution of Covered Software in Source Code Form, including any
Modifications that You create or to which You contribute, must be under
the terms of this License. You must inform recipients that the Source
Code Form of the Covered Software is governed by the terms of this
License, and how they can obtain a copy of this License. You may not
attempt to alter or restrict the recipients' rights in the Source Code
Form.
3.2. Distribution of Executable Form
If You distribute Covered Software in Executable Form then:
(a) such Covered Software must also be made available in Source Code
Form, as described in Section 3.1, and You must inform recipients of
the Executable Form how they can obtain a copy of such Source Code
Form by reasonable means in a timely manner, at a charge no more
than the cost of distribution to the recipient; and
(b) You may distribute such Executable Form under the terms of this
License, or sublicense it under different terms, provided that the
license for the Executable Form does not attempt to limit or alter
the recipients' rights in the Source Code Form under this License.
3.3. Distribution of a Larger Work
You may create and distribute a Larger Work under terms of Your choice,
provided that You also comply with the requirements of this License for
the Covered Software. If the Larger Work is a combination of Covered
Software with a work governed by one or more Secondary Licenses, and the
Covered Software is not Incompatible With Secondary Licenses, this
License permits You to additionally distribute such Covered Software
under the terms of such Secondary License(s), so that the recipient of
the Larger Work may, at their option, further distribute the Covered
Software under the terms of either this License or such Secondary
License(s).
3.4. Notices
You may not remove or alter the substance of any license notices
(including copyright notices, patent notices, disclaimers of warranty,
or limitations of liability) contained within the Source Code Form of
the Covered Software, except that You may alter any license notices to
the extent required to remedy known factual inaccuracies.
3.5. Application of Additional Terms
You may choose to offer, and to charge a fee for, warranty, support,
indemnity or liability obligations to one or more recipients of Covered
Software. However, You may do so only on Your own behalf, and not on
behalf of any Contributor. You must make it absolutely clear that any
such warranty, support, indemnity, or liability obligation is offered by
You alone, and You hereby agree to indemnify every Contributor for any
liability incurred by such Contributor as a result of warranty, support,
indemnity or liability terms You offer. You may include additional
disclaimers of warranty and limitations of liability specific to any
jurisdiction.
4. Inability to Comply Due to Statute or Regulation
---------------------------------------------------
If it is impossible for You to comply with any of the terms of this
License with respect to some or all of the Covered Software due to
statute, judicial order, or regulation then You must: (a) comply with
the terms of this License to the maximum extent possible; and (b)
describe the limitations and the code they affect. Such description must
be placed in a text file included with all distributions of the Covered
Software under this License. Except to the extent prohibited by statute
or regulation, such description must be sufficiently detailed for a
recipient of ordinary skill to be able to understand it.
5. Termination
--------------
5.1. The rights granted under this License will terminate automatically
if You fail to comply with any of its terms. However, if You become
compliant, then the rights granted under this License from a particular
Contributor are reinstated (a) provisionally, unless and until such
Contributor explicitly and finally terminates Your grants, and (b) on an
ongoing basis, if such Contributor fails to notify You of the
non-compliance by some reasonable means prior to 60 days after You have
come back into compliance. Moreover, Your grants from a particular
Contributor are reinstated on an ongoing basis if such Contributor
notifies You of the non-compliance by some reasonable means, this is the
first time You have received notice of non-compliance with this License
from such Contributor, and You become compliant prior to 30 days after
Your receipt of the notice.
5.2. If You initiate litigation against any entity by asserting a patent
infringement claim (excluding declaratory judgment actions,
counter-claims, and cross-claims) alleging that a Contributor Version
directly or indirectly infringes any patent, then the rights granted to
You by any and all Contributors for the Covered Software under Section
2.1 of this License shall terminate.
5.3. In the event of termination under Sections 5.1 or 5.2 above, all
end user license agreements (excluding distributors and resellers) which
have been validly granted by You or Your distributors under this License
prior to termination shall survive termination.
************************************************************************
* *
* 6. Disclaimer of Warranty *
* ------------------------- *
* *
* Covered Software is provided under this License on an "as is" *
* basis, without warranty of any kind, either expressed, implied, or *
* statutory, including, without limitation, warranties that the *
* Covered Software is free of defects, merchantable, fit for a *
* particular purpose or non-infringing. The entire risk as to the *
* quality and performance of the Covered Software is with You. *
* Should any Covered Software prove defective in any respect, You *
* (not any Contributor) assume the cost of any necessary servicing, *
* repair, or correction. This disclaimer of warranty constitutes an *
* essential part of this License. No use of any Covered Software is *
* authorized under this License except under this disclaimer. *
* *
************************************************************************
************************************************************************
* *
* 7. Limitation of Liability *
* -------------------------- *
* *
* Under no circumstances and under no legal theory, whether tort *
* (including negligence), contract, or otherwise, shall any *
* Contributor, or anyone who distributes Covered Software as *
* permitted above, be liable to You for any direct, indirect, *
* special, incidental, or consequential damages of any character *
* including, without limitation, damages for lost profits, loss of *
* goodwill, work stoppage, computer failure or malfunction, or any *
* and all other commercial damages or losses, even if such party *
* shall have been informed of the possibility of such damages. This *
* limitation of liability shall not apply to liability for death or *
* personal injury resulting from such party's negligence to the *
* extent applicable law prohibits such limitation. Some *
* jurisdictions do not allow the exclusion or limitation of *
* incidental or consequential damages, so this exclusion and *
* limitation may not apply to You. *
* *
************************************************************************
8. Litigation
-------------
Any litigation relating to this License may be brought only in the
courts of a jurisdiction where the defendant maintains its principal
place of business and such litigation shall be governed by laws of that
jurisdiction, without reference to its conflict-of-law provisions.
Nothing in this Section shall prevent a party's ability to bring
cross-claims or counter-claims.
9. Miscellaneous
----------------
This License represents the complete agreement concerning the subject
matter hereof. If any provision of this License is held to be
unenforceable, such provision shall be reformed only to the extent
necessary to make it enforceable. Any law or regulation which provides
that the language of a contract shall be construed against the drafter
shall not be used to construe this License against a Contributor.
10. Versions of the License
---------------------------
10.1. New Versions
Mozilla Foundation is the license steward. Except as provided in Section
10.3, no one other than the license steward has the right to modify or
publish new versions of this License. Each version will be given a
distinguishing version number.
10.2. Effect of New Versions
You may distribute the Covered Software under the terms of the version
of the License under which You originally received the Covered Software,
or under the terms of any subsequent version published by the license
steward.
10.3. Modified Versions
If you create software not governed by this License, and you want to
create a new license for such software, you may create and use a
modified version of this License if you rename the license and remove
any references to the name of the license steward (except to note that
such modified license differs from this License).
10.4. Distributing Source Code Form that is Incompatible With Secondary
Licenses
If You choose to distribute Source Code Form that is Incompatible With
Secondary Licenses under the terms of this version of the License, the
notice described in Exhibit B of this License must be attached.
Exhibit A - Source Code Form License Notice
-------------------------------------------
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at https://mozilla.org/MPL/2.0/.
If it is not possible or desirable to put the notice in a particular
file, then You may include the notice in a location (such as a LICENSE
file in a relevant directory) where a recipient would be likely to look
for such a notice.
You may add additional accurate notices of copyright ownership.
Exhibit B - "Incompatible With Secondary Licenses" Notice
---------------------------------------------------------
This Source Code Form is "Incompatible With Secondary Licenses", as
defined by the Mozilla Public License, v. 2.0.
Requirements and compatibility
Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta
“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.
Needs: Needs a command-line tool
Security
No issues found by our static scan· No issues found
A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.
Attribution and licence
- Published by
- HashiCorp
- Publisher
- HashiCorp (Official)
- Source
- hashicorp/agent-skills · plugins/terraform/skills/terraform-test · commit 5e30fa5
- Licence
- Mozilla Public License 2.0 (redistribution allowed)
- LICENSE (added by AutoGineer from LICENSE)
- ATTRIBUTION.md (written by AutoGineer)
- Synced
AutoGineer is not affiliated with or endorsed by HashiCorp.
Download ZIP
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