diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3b2b4d1e9..44ac9ab01 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -24,7 +24,7 @@ The Coder Registry is a collection of Terraform modules and templates for Coder
 
 ### Install Dependencies
 
-Install Bun:
+Install Bun (for formatting and scripts):
 
 ```bash
 curl -fsSL https://bun.sh/install | bash
@@ -124,19 +124,23 @@ This script generates:
    - Accurate description and usage examples
    - Correct icon path (usually `../../../../.icons/your-icon.svg`)
    - Proper tags that describe your module
-3. **Create `main.test.ts`** to test your module
+3. **Create at least one `.tftest.hcl`** to test your module with `terraform test`
 4. **Add any scripts** or additional files your module needs
 
 ### 4. Test and Submit
 
 ```bash
-# Test your module
-bun test -t 'module-name'
+# Test your module (from the module directory)
+terraform init -upgrade
+terraform test -verbose
+
+# Or run all tests in the repo
+./scripts/terraform_test_all.sh
 
 # Format code
-bun fmt
+bun run fmt
 
-# Commit and create PR
+# Commit and create PR (do not push to main directly)
 git add .
 git commit -m "Add [module-name] module"
 git push origin your-branch
@@ -335,11 +339,12 @@ coder templates push test-[template-name] -d .
 ### 2. Test Your Changes
 
 ```bash
-# Test a specific module
-bun test -t 'module-name'
+# Test a specific module (from the module directory)
+terraform init -upgrade
+terraform test -verbose
 
 # Test all modules
-bun test
+./scripts/terraform_test_all.sh
 ```
 
 ### 3. Maintain Backward Compatibility
@@ -388,7 +393,7 @@ Example: `https://github.com/coder/registry/compare/main...your-branch?template=
 ### Every Module Must Have
 
 - `main.tf` - Terraform code
-- `main.test.ts` - Working tests
+- One or more `.tftest.hcl` files - Working tests with `terraform test`
 - `README.md` - Documentation with frontmatter
 
 ### Every Template Must Have
@@ -488,6 +493,6 @@ When reporting bugs, include:
 2. **No tests** or broken tests
 3. **Hardcoded values** instead of variables
 4. **Breaking changes** without defaults
-5. **Not running** `bun fmt` before submitting
+5. **Not running** formatting (`bun run fmt`) and tests (`terraform test`) before submitting
 
 Happy contributing! 🚀
diff --git a/MAINTAINER.md b/MAINTAINER.md
index 223265746..9959e59c8 100644
--- a/MAINTAINER.md
+++ b/MAINTAINER.md
@@ -18,9 +18,9 @@ sudo apt install golang-go
 
 Check that PRs have:
 
-- [ ] All required files (`main.tf`, `main.test.ts`, `README.md`)
+- [ ] All required files (`main.tf`, `README.md`, at least one `.tftest.hcl`)
 - [ ] Proper frontmatter in README
-- [ ] Working tests (`bun test`)
+- [ ] Working tests (`terraform test`)
 - [ ] Formatted code (`bun run fmt`)
 - [ ] Avatar image for new namespaces (`avatar.png` or `avatar.svg` in `.images/`)
 
diff --git a/examples/modules/MODULE_NAME.tftest.hcl b/examples/modules/MODULE_NAME.tftest.hcl
new file mode 100644
index 000000000..6f11666b5
--- /dev/null
+++ b/examples/modules/MODULE_NAME.tftest.hcl
@@ -0,0 +1,21 @@
+run "plan_with_required_vars" {
+  command = plan
+
+  variables {
+    agent_id = "example-agent-id"
+  }
+}
+
+run "app_url_uses_port" {
+  command = plan
+
+  variables {
+    agent_id = "example-agent-id"
+    port     = 19999
+  }
+
+  assert {
+    condition     = resource.coder_app.MODULE_NAME.url == "http://localhost:19999"
+    error_message = "Expected MODULE_NAME app URL to include configured port"
+  }
+}
diff --git a/package.json b/package.json
index 7ca9f2ec2..c2f9ff694 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
     "fmt": "bun x prettier --write **/*.sh **/*.ts **/*.md *.md && terraform fmt -recursive -diff",
     "fmt:ci": "bun x prettier --check **/*.sh **/*.ts **/*.md *.md && terraform fmt -check -recursive -diff",
     "terraform-validate": "./scripts/terraform_validate.sh",
-    "test": "bun test",
+    "test": "./scripts/terraform_test_all.sh",
     "update-version": "./update-version.sh"
   },
   "devDependencies": {
diff --git a/registry/coder/modules/code-server/code-server.tftest.hcl b/registry/coder/modules/code-server/code-server.tftest.hcl
new file mode 100644
index 000000000..ebbb71755
--- /dev/null
+++ b/registry/coder/modules/code-server/code-server.tftest.hcl
@@ -0,0 +1,50 @@
+run "required_vars" {
+  command = plan
+
+  variables {
+    agent_id = "foo"
+  }
+}
+
+run "offline_and_use_cached_conflict" {
+  command = plan
+
+  variables {
+    agent_id   = "foo"
+    use_cached = true
+    offline    = true
+  }
+
+  expect_failures = [
+    resource.coder_script.code-server
+  ]
+}
+
+run "offline_disallows_extensions" {
+  command = plan
+
+  variables {
+    agent_id   = "foo"
+    offline    = true
+    extensions = ["ms-python.python", "golang.go"]
+  }
+
+  expect_failures = [
+    resource.coder_script.code-server
+  ]
+}
+
+run "url_with_folder_query" {
+  command = plan
+
+  variables {
+    agent_id = "foo"
+    folder   = "/home/coder/project"
+    port     = 13337
+  }
+
+  assert {
+    condition     = resource.coder_app.code-server.url == "http://localhost:13337/?folder=%2Fhome%2Fcoder%2Fproject"
+    error_message = "coder_app URL must include encoded folder query param"
+  }
+}
diff --git a/registry/coder/modules/jetbrains/jetbrains.tftest.hcl b/registry/coder/modules/jetbrains/jetbrains.tftest.hcl
new file mode 100644
index 000000000..e5c00a78e
--- /dev/null
+++ b/registry/coder/modules/jetbrains/jetbrains.tftest.hcl
@@ -0,0 +1,131 @@
+run "requires_agent_and_folder" {
+  command = plan
+
+  # Setting both required vars should plan
+  variables {
+    agent_id = "foo"
+    folder   = "/home/coder"
+  }
+}
+
+run "creates_parameter_when_default_empty_latest" {
+  command = plan
+
+  variables {
+    agent_id      = "foo"
+    folder        = "/home/coder"
+    major_version = "latest"
+  }
+
+  # When default is empty, a coder_parameter should be created
+  assert {
+    condition     = can(data.coder_parameter.jetbrains_ides[0].type)
+    error_message = "Expected data.coder_parameter.jetbrains_ides to exist when default is empty"
+  }
+}
+
+run "no_apps_when_default_empty" {
+  command = plan
+
+  variables {
+    agent_id = "foo"
+    folder   = "/home/coder"
+  }
+
+  assert {
+    condition     = length(resource.coder_app.jetbrains) == 0
+    error_message = "Expected no coder_app resources when default is empty"
+  }
+}
+
+run "single_app_when_default_GO" {
+  command = plan
+
+  variables {
+    agent_id = "foo"
+    folder   = "/home/coder"
+    default  = ["GO"]
+  }
+
+  assert {
+    condition     = length(resource.coder_app.jetbrains) == 1
+    error_message = "Expected exactly one coder_app when default contains GO"
+  }
+}
+
+run "url_contains_required_params" {
+  command = apply
+
+  variables {
+    agent_id = "test-agent-123"
+    folder   = "/custom/project/path"
+    default  = ["GO"]
+  }
+
+  assert {
+    condition     = anytrue([for app in values(resource.coder_app.jetbrains) : length(regexall("jetbrains://gateway/coder", app.url)) > 0])
+    error_message = "URL must contain jetbrains scheme"
+  }
+
+  assert {
+    condition     = anytrue([for app in values(resource.coder_app.jetbrains) : length(regexall("&folder=/custom/project/path", app.url)) > 0])
+    error_message = "URL must include folder path"
+  }
+
+  assert {
+    condition     = anytrue([for app in values(resource.coder_app.jetbrains) : length(regexall("ide_product_code=GO", app.url)) > 0])
+    error_message = "URL must include product code"
+  }
+
+  assert {
+    condition     = anytrue([for app in values(resource.coder_app.jetbrains) : length(regexall("ide_build_number=", app.url)) > 0])
+    error_message = "URL must include build number"
+  }
+}
+
+run "includes_agent_name_when_set" {
+  command = apply
+
+  variables {
+    agent_id   = "test-agent-123"
+    agent_name = "main-agent"
+    folder     = "/custom/project/path"
+    default    = ["GO"]
+  }
+
+  assert {
+    condition     = anytrue([for app in values(resource.coder_app.jetbrains) : length(regexall("&agent_name=main-agent", app.url)) > 0])
+    error_message = "URL must include agent_name when provided"
+  }
+}
+
+run "parameter_order_when_default_empty" {
+  command = plan
+
+  variables {
+    agent_id              = "foo"
+    folder                = "/home/coder"
+    coder_parameter_order = 5
+  }
+
+  assert {
+    condition     = data.coder_parameter.jetbrains_ides[0].order == 5
+    error_message = "Expected coder_parameter order to be set to 5"
+  }
+}
+
+run "app_order_when_default_not_empty" {
+  command = plan
+
+  variables {
+    agent_id        = "foo"
+    folder          = "/home/coder"
+    default         = ["GO"]
+    coder_app_order = 10
+  }
+
+  assert {
+    condition     = anytrue([for app in values(resource.coder_app.jetbrains) : app.order == 10])
+    error_message = "Expected coder_app order to be set to 10"
+  }
+}
diff --git a/registry/coder/modules/zed/zed.tftest.hcl b/registry/coder/modules/zed/zed.tftest.hcl
new file mode 100644
index 000000000..508b65503
--- /dev/null
+++ b/registry/coder/modules/zed/zed.tftest.hcl
@@ -0,0 +1,40 @@
+run "default_output" {
+  command = apply
+
+  variables {
+    agent_id = "foo"
+  }
+
+  assert {
+    condition     = output.zed_url == "zed://ssh/default.coder"
+    error_message = "zed_url did not match expected default URL"
+  }
+}
+
+run "adds_folder" {
+  command = apply
+
+  variables {
+    agent_id = "foo"
+    folder   = "/foo/bar"
+  }
+
+  assert {
+    condition     = output.zed_url == "zed://ssh/default.coder/foo/bar"
+    error_message = "zed_url did not include provided folder path"
+  }
+}
+
+run "adds_agent_name" {
+  command = apply
+
+  variables {
+    agent_id   = "foo"
+    agent_name = "myagent"
+  }
+
+  assert {
+    condition     = output.zed_url == "zed://ssh/myagent.default.default.coder"
+    error_message = "zed_url did not include agent_name in hostname"
+  }
+}
diff --git a/scripts/terraform_test_all.sh b/scripts/terraform_test_all.sh
new file mode 100755
index 000000000..01258904d
--- /dev/null
+++ b/scripts/terraform_test_all.sh
@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Find all directories that contain any .tftest.hcl files and run terraform test in each
+
+run_dir() {
+  local dir="$1"
+  echo "==> Running terraform test in $dir"
+  (cd "$dir" && terraform init -upgrade -input=false -no-color > /dev/null && terraform test -no-color -verbose)
+}
+
+mapfile -t test_dirs < <(find . -type f -name "*.tftest.hcl" -print0 | xargs -0 -I{} dirname {} | sort -u)
+
+if [[ ${#test_dirs[@]} -eq 0 ]]; then
+  echo "No .tftest.hcl tests found."
+  exit 0
+fi
+
+status=0
+for d in "${test_dirs[@]}"; do
+  if ! run_dir "$d"; then
+    status=1
+  fi
+done
+
+exit $status