terraform test: refactor the context initialisation into specific node in the graph

Author: Liam Cervante

internal/backend/local/test.go

@@ -7,13 +7,10 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"maps"
 	"path/filepath"
 	"slices"
 
-	"github.com/zclconf/go-cty/cty"
-
-	"maps"
-
 	"github.com/hashicorp/terraform/internal/backend/backendrun"
 	"github.com/hashicorp/terraform/internal/command/junit"
 	"github.com/hashicorp/terraform/internal/command/views"
@@ -113,28 +110,22 @@ func (runner *TestSuiteRunner) Test() (moduletest.Status, tfdiags.Diagnostics) {
 		}
 
 		file := suite.Files[name]
-		evalCtx := graph.NewEvalContext(&graph.EvalContextOpts{
+		evalCtx := graph.NewEvalContext(graph.EvalContextOpts{
 			CancelCtx: runner.CancelledCtx,
 			StopCtx:   runner.StoppedCtx,
 			Verbose:   runner.Verbose,
 			Render:    runner.View,
 		})
 
-		for _, run := range file.Runs {
-			// Pre-initialise the prior outputs, so we can easily tell between
-			// a run block that doesn't exist and a run block that hasn't been
-			// executed yet.
-			// (moduletest.EvalContext treats cty.NilVal as "not visited yet")
-			evalCtx.SetOutput(run, cty.NilVal)
-		}
+		// TODO(liamcervante): Do the variables in the EvalContextTransformer
+		// as well as the run blocks.
 
 		currentGlobalVariables := runner.GlobalVariables
 		if filepath.Dir(file.Name) == runner.TestingDirectory {
 			// If the file is in the test directory, we'll use the union of the
 			// global variables and the global test variables.
 			currentGlobalVariables = testDirectoryGlobalVariables
 		}
-
 		evalCtx.VariableCaches = hcltest.NewVariableCaches(func(vc *hcltest.VariableCaches) {
 			maps.Copy(vc.GlobalVariables, currentGlobalVariables)
 			vc.FileVariables = file.Config.Variables

internal/moduletest/graph/eval_context.go

@@ -7,15 +7,14 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"maps"
 	"sort"
 	"sync"
 
 	"github.com/hashicorp/hcl/v2"
 	"github.com/zclconf/go-cty/cty"
 	"github.com/zclconf/go-cty/cty/convert"
 
-	"maps"
-
 	"github.com/hashicorp/terraform/internal/addrs"
 	"github.com/hashicorp/terraform/internal/command/views"
 	"github.com/hashicorp/terraform/internal/configs"
@@ -24,10 +23,18 @@ import (
 	"github.com/hashicorp/terraform/internal/lang/langrefs"
 	"github.com/hashicorp/terraform/internal/moduletest"
 	hcltest "github.com/hashicorp/terraform/internal/moduletest/hcl"
+	"github.com/hashicorp/terraform/internal/states"
 	"github.com/hashicorp/terraform/internal/terraform"
 	"github.com/hashicorp/terraform/internal/tfdiags"
 )
 
+// TestFileState is a helper struct that just maps a run block to the state that
+// was produced by the execution of that run block.
+type TestFileState struct {
+	Run   *moduletest.Run
+	State *states.State
+}
+
 // EvalContext is a container for context relating to the evaluation of a
 // particular .tftest.hcl file.
 // This context is used to track the various values that are available to the
@@ -87,7 +94,7 @@ type EvalContextOpts struct {
 // evaluating the runs within a test suite.
 // The context is initialized with the provided cancel and stop contexts, and
 // these contexts can be used from external commands to signal the termination of the test suite.
-func NewEvalContext(opts *EvalContextOpts) *EvalContext {
+func NewEvalContext(opts EvalContextOpts) *EvalContext {
 	cancelCtx, cancel := context.WithCancel(opts.CancelCtx)
 	stopCtx, stop := context.WithCancel(opts.StopCtx)
 	return &EvalContext{

internal/moduletest/graph/eval_context_test.go

@@ -735,7 +735,7 @@ func TestEvalContext_Evaluate(t *testing.T) {
 				priorOutputs[addrs.Run{Name: name}] = val
 			}
 
-			testCtx := NewEvalContext(&EvalContextOpts{
+			testCtx := NewEvalContext(EvalContextOpts{
 				CancelCtx: context.Background(),
 				StopCtx:   context.Background(),
 			})

internal/moduletest/graph/test_graph_builder.go

@@ -13,6 +13,10 @@ import (
 	"github.com/hashicorp/terraform/internal/tfdiags"
 )
 
+type GraphNodeExecutable interface {
+	Execute(ctx *EvalContext) tfdiags.Diagnostics
+}
+
 // TestGraphBuilder is a GraphBuilder implementation that builds a graph for
 // a terraform test file. The file may contain multiple runs, and each run may have
 // dependencies on other runs.
@@ -46,11 +50,11 @@ func (b *TestGraphBuilder) Steps() []terraform.GraphTransformer {
 	}
 	steps := []terraform.GraphTransformer{
 		&TestRunTransformer{opts},
-		&TestConfigTransformer{File: b.File},
 		&TestStateCleanupTransformer{opts},
 		terraform.DynamicTransformer(validateRunConfigs),
 		&TestProvidersTransformer{},
 		&CloseTestGraphTransformer{},
+		&EvalContextTransformer{File: b.File},
 		&terraform.TransitiveReductionTransformer{},
 	}
 

internal/moduletest/graph/transform_config.go

@@ -7,81 +7,22 @@ import (
 	"fmt"
 
 	"github.com/hashicorp/hcl/v2"
+
 	"github.com/hashicorp/terraform/internal/configs"
-	"github.com/hashicorp/terraform/internal/dag"
 	"github.com/hashicorp/terraform/internal/moduletest"
 	hcltest "github.com/hashicorp/terraform/internal/moduletest/hcl"
-	"github.com/hashicorp/terraform/internal/states"
-	"github.com/hashicorp/terraform/internal/terraform"
-	"github.com/hashicorp/terraform/internal/tfdiags"
 )
 
-type GraphNodeExecutable interface {
-	Execute(ctx *EvalContext) tfdiags.Diagnostics
-}
-
-// TestFileState is a helper struct that just maps a run block to the state that
-// was produced by the execution of that run block.
-type TestFileState struct {
-	Run   *moduletest.Run
-	State *states.State
-}
-
-// TestConfigTransformer is a GraphTransformer that adds all the test runs,
-// and the variables defined in each run block, to the graph.
-type TestConfigTransformer struct {
-	File *moduletest.File
-}
-
-func (t *TestConfigTransformer) Transform(g *terraform.Graph) error {
-	// This map tracks the state of each run in the file. If multiple runs
-	// have the same state key, they will share the same state.
-	statesMap := make(map[string]*TestFileState)
-
-	// a root config node that will add the file states to the context
-	rootConfigNode := t.addRootConfigNode(g, statesMap)
-
-	for _, v := range g.Vertices() {
-		node, ok := v.(*NodeTestRun)
-		if !ok {
-			continue
-		}
-		key := node.run.GetStateKey()
-		if _, exists := statesMap[key]; !exists {
-			state := &TestFileState{
-				Run:   nil,
-				State: states.NewState(),
-			}
-			statesMap[key] = state
-		}
-
-		// Connect all the test runs to the config node, so that the config node
-		// is executed before any of the test runs.
-		g.Connect(dag.BasicEdge(node, rootConfigNode))
-	}
-
-	return nil
-}
-
-func (t *TestConfigTransformer) addRootConfigNode(g *terraform.Graph, statesMap map[string]*TestFileState) *dynamicNode {
-	rootConfigNode := &dynamicNode{
-		eval: func(ctx *EvalContext) tfdiags.Diagnostics {
-			var diags tfdiags.Diagnostics
-			ctx.FileStates = statesMap
-			return diags
-		},
-	}
-	g.Add(rootConfigNode)
-	return rootConfigNode
-}
-
 // TransformConfigForRun transforms the run's module configuration to include
 // the providers and variables from its block and the test file.
 //
 // In practice, this actually just means performing some surgery on the
 // available providers. We want to copy the relevant providers from the test
 // file into the configuration. We also want to process the providers so they
 // use variables from the file instead of variables from within the test file.
+//
+// TODO(liamcervante): Push provider initialisation into the test graph
+// so we don't have to transform the config in this way anymore.
 func TransformConfigForRun(ctx *EvalContext, run *moduletest.Run, file *moduletest.File) hcl.Diagnostics {
 	var diags hcl.Diagnostics
 

internal/moduletest/graph/transform_config_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/hcl/v2/hclparse"
+
 	"github.com/hashicorp/terraform/internal/configs"
 	"github.com/hashicorp/terraform/internal/moduletest"
 )
@@ -219,7 +220,7 @@ func TestTransformForTest(t *testing.T) {
 				availableProviders[provider] = true
 			}
 
-			ctx := NewEvalContext(&EvalContextOpts{
+			ctx := NewEvalContext(EvalContextOpts{
 				CancelCtx: context.Background(),
 				StopCtx:   context.Background(),
 			})

internal/moduletest/graph/transform_context.go

@@ -0,0 +1,63 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package graph
+
+import (
+	"github.com/zclconf/go-cty/cty"
+
+	"github.com/hashicorp/terraform/internal/dag"
+	"github.com/hashicorp/terraform/internal/moduletest"
+	"github.com/hashicorp/terraform/internal/states"
+	"github.com/hashicorp/terraform/internal/terraform"
+	"github.com/hashicorp/terraform/internal/tfdiags"
+)
+
+var _ terraform.GraphTransformer = (*EvalContextTransformer)(nil)
+
+// EvalContextTransformer should be the first node to execute in the graph, and
+// it initialises the run blocks and state files in the evaluation context.
+// TODO(liamcervante): Also initialise the variables in here when needed.
+type EvalContextTransformer struct {
+	File *moduletest.File
+}
+
+func (e *EvalContextTransformer) Transform(graph *terraform.Graph) error {
+	node := &dynamicNode{
+		eval: func(ctx *EvalContext) tfdiags.Diagnostics {
+			for _, run := range e.File.Runs {
+
+				// Within the run outputs a nil but present entry means the
+				// run block exists but hasn't executed yet.
+				// TODO(liamcervante): Once providers are embedded in the graph
+				// we don't need to track run blocks in this way anymore.
+
+				ctx.SetOutput(run, cty.NilVal)
+
+				// We also want to set an empty state file for every state key
+				// we're going to be executing within the graph.
+
+				key := run.GetStateKey()
+				if state := ctx.GetFileState(key); state == nil {
+					ctx.SetFileState(key, &TestFileState{
+						Run:   nil,
+						State: states.NewState(),
+					})
+				}
+
+			}
+
+			return nil
+		},
+	}
+
+	graph.Add(node)
+	for _, v := range graph.Vertices() {
+		if v == node {
+			continue
+		}
+		graph.Connect(dag.BasicEdge(v, node))
+	}
+
+	return nil
+}

internal/moduletest/graph/transform_providers.go

@@ -59,7 +59,7 @@ func (t *TestProvidersTransformer) transformSingleConfig(config *configs.Config)
 		providers[provider.Addr().StringCompact()] = true
 	}
 
-	// Third, we look at the resources and data sources.
+	// Third, we look at the resources and data sources.g
 	for _, resource := range config.Module.ManagedResources {
 		if resource.ProviderConfigRef != nil {
 			providers[resource.ProviderConfigRef.String()] = true