terraform test: Collect variables from default var file within testin…

…g directory (#34341)

* Add logic to collect variables for terrafrom test

* Add tests for test variable collection

* Update the test variable collection implementation

* Update internal/backend/local/test.go

Co-authored-by: Liam Cervante <liam.cervante@hashicorp.com>

* Update internal/backend/local/test.go

Co-authored-by: Liam Cervante <liam.cervante@hashicorp.com>

* Move test variables into var file

* resolve diff from cross-branch switch

* go fmt

---------

Co-authored-by: Liam Cervante <liam.cervante@hashicorp.com>

internal/backend/local/test.go

@@ -39,8 +39,14 @@ const (
 type TestSuiteRunner struct {
 	Config *configs.Config
 
-	GlobalVariables map[string]backend.UnparsedVariableValue
-	Opts            *terraform.ContextOpts
+	TestingDirectory string
+
+	// Global variables comes from the main configuration directory,
+	// and the Global Test Variables are loaded from the test directory.
+	GlobalVariables     map[string]backend.UnparsedVariableValue
+	GlobalTestVariables map[string]backend.UnparsedVariableValue
+
+	Opts *terraform.ContextOpts
 
 	View views.Test
 
@@ -1233,6 +1239,14 @@ func (runner *TestFileRunner) initVariables(file *moduletest.File) {
 	for name, value := range runner.Suite.GlobalVariables {
 		runner.globalVariables[name] = value
 	}
+	if path.Dir(file.Name) == runner.Suite.TestingDirectory {
+		// If the file is in the testing directory, then also include any
+		// variables that are defined within the default variable file also in
+		// the test directory.
+		for name, value := range runner.Suite.GlobalTestVariables {
+			runner.globalVariables[name] = value
+		}
+	}
 	for name, expr := range file.Config.Variables {
 		runner.globalVariables[name] = unparsedTestVariableValue{expr}
 	}

internal/command/meta_vars.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
@@ -23,6 +24,51 @@ import (
 // for root module input variables.
 const VarEnvPrefix = "TF_VAR_"
 
+// collectVariableValuesForTests inspects the various places that test
+// values can come from and constructs a map ready to be passed to the
+// backend as part of a backend.Operation.
+//
+// This method returns diagnostics relating to the collection of the values,
+// but the values themselves may produce additional diagnostics when finally
+// parsed.
+func (m *Meta) collectVariableValuesForTests(testsFilePath string) (map[string]backend.UnparsedVariableValue, tfdiags.Diagnostics) {
+	var diags tfdiags.Diagnostics
+	ret := map[string]backend.UnparsedVariableValue{}
+
+	// We collect the variables from the ./tests directory
+	// there is no other need to process environmental variables
+	// as this is done via collectVariableValues function
+	if testsFilePath == "" {
+		diags = diags.Append(tfdiags.Sourceless(
+			tfdiags.Warning,
+			"Missing test directory",
+			"The test directory was unspecified when it should always be set. This is a bug in Terraform - please report it."))
+		return ret, diags
+	}
+
+	// Firstly we collect variables from .tfvars file
+	testVarsFilename := filepath.Join(testsFilePath, DefaultVarsFilename)
+	if _, err := os.Stat(testVarsFilename); err == nil {
+		moreDiags := m.addVarsFromFile(testVarsFilename, terraform.ValueFromAutoFile, ret)
+		diags = diags.Append(moreDiags)
+
+	}
+
+	// Then we collect variables from .tfvars.json file
+	const defaultVarsFilenameJSON = DefaultVarsFilename + ".json"
+	testVarsFilenameJSON := filepath.Join(testsFilePath, defaultVarsFilenameJSON)
+
+	if _, err := os.Stat(testVarsFilenameJSON); err == nil {
+		moreDiags := m.addVarsFromFile(testVarsFilenameJSON, terraform.ValueFromAutoFile, ret)
+		diags = diags.Append(moreDiags)
+	}
+
+	// Also, no need to additionally process variables from command line,
+	// as this is also done via collectVariableValues
+
+	return ret, diags
+}
+
 // collectVariableValues inspects the various places that root module input variable
 // values can come from and constructs a map ready to be passed to the
 // backend as part of a backend.Operation.

internal/command/test.go

@@ -130,6 +130,10 @@ func (c *TestCommand) Run(rawArgs []string) int {
 	}
 	c.variableArgs = rawFlags{items: &items}
 
+	// Collect variables for "terraform test"
+	testVariables, variableDiags := c.collectVariableValuesForTests(args.TestDirectory)
+	diags = diags.Append(variableDiags)
+
 	variables, variableDiags := c.collectVariableValues()
 	diags = diags.Append(variableDiags)
 	if variableDiags.HasErrors() {
@@ -195,16 +199,22 @@ func (c *TestCommand) Run(rawArgs []string) int {
 		}
 	} else {
 		runner = &local.TestSuiteRunner{
-			Config:          config,
-			GlobalVariables: variables,
-			Opts:            opts,
-			View:            view,
-			Stopped:         false,
-			Cancelled:       false,
-			StoppedCtx:      stopCtx,
-			CancelledCtx:    cancelCtx,
-			Filter:          args.Filter,
-			Verbose:         args.Verbose,
+			Config: config,
+			// The GlobalVariables are loaded from the
+			// main configuration directory
+			// The GlobalTestVariables are loaded from the
+			// test directory
+			GlobalVariables:     variables,
+			GlobalTestVariables: testVariables,
+			TestingDirectory:    args.TestDirectory,
+			Opts:                opts,
+			View:                view,
+			Stopped:             false,
+			Cancelled:           false,
+			StoppedCtx:          stopCtx,
+			CancelledCtx:        cancelCtx,
+			Filter:              args.Filter,
+			Verbose:             args.Verbose,
 		}
 	}
 

internal/command/test_test.go

@@ -197,6 +197,10 @@ func TestTest_Runs(t *testing.T) {
 			expectedOut: "4 passed, 0 failed.",
 			code:        0,
 		},
+		"tfvars_in_test_dir": {
+			expectedOut: "2 passed, 0 failed.",
+			code:        0,
+		},
 		"functions_available": {
 			expectedOut: "1 passed, 0 failed.",
 			code:        0,

internal/command/testdata/test/tfvars_in_test_dir/main.tf

@@ -0,0 +1,17 @@
+variable "foo" {
+  description = "This is test variable"
+  default = "def_value"
+}
+
+variable "fooJSON" {
+  description = "This is test variable"
+  default = "def_value"
+}
+
+output "out_foo" {
+  value = var.foo
+}
+
+output "out_fooJSON" {
+  value = var.fooJSON
+}

internal/command/testdata/test/tfvars_in_test_dir/tests/main.tftest.hcl

@@ -0,0 +1,13 @@
+run "primary" {
+  assert {
+    condition     = var.foo == var.test_foo
+    error_message = "Expected: ${var.test_foo}, Actual: ${var.foo}"
+  }
+}
+
+run "secondary" {
+    assert {
+      condition     = var.fooJSON == var.test_foo_json
+      error_message = "Expected: ${var.test_foo_json}, Actual: ${var.fooJSON}"
+    }
+}

internal/command/testdata/test/tfvars_in_test_dir/tests/terraform.tfvars

@@ -0,0 +1,3 @@
+foo = "foo_tfvars_value"
+test_foo = "foo_tfvars_value"
+test_foo_json = "foo_json_tfvars_value"

internal/command/testdata/test/tfvars_in_test_dir/tests/terraform.tfvars.json

@@ -0,0 +1,3 @@
+{
+    "fooJSON": "foo_json_tfvars_value"
+}