terraform console: enable use of impure functions (#25442)

* command/console: allow use of impure functions in terraform console
* add tests for Context Eval

Author: mildwonkey

terraform/context_eval_test.go

@@ -0,0 +1,85 @@
+package terraform
+
+import (
+	"testing"
+
+	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
+	"github.com/hashicorp/terraform/addrs"
+	"github.com/hashicorp/terraform/providers"
+	"github.com/zclconf/go-cty/cty"
+)
+
+func TestContextEval(t *testing.T) {
+	// This test doesn't check the "Want" value for impure funcs, so the value
+	// on those doesn't matter.
+	tests := []struct {
+		Input      string
+		Want       cty.Value
+		ImpureFunc bool
+	}{
+		{ // An impure function: allowed in the console, but the result is nondeterministic
+			`bcrypt("example")`,
+			cty.NilVal,
+			true,
+		},
+		{
+			`keys(var.map)`,
+			cty.ListVal([]cty.Value{
+				cty.StringVal("foo"),
+				cty.StringVal("baz"),
+			}),
+			true,
+		},
+		{
+			`local.result`,
+			cty.NumberIntVal(6),
+			false,
+		},
+		{
+			`module.child.result`,
+			cty.UnknownVal(cty.Number),
+			false,
+		},
+	}
+
+	// This module has a little bit of everything (and if it is missing somehitng, add to it):
+	// resources, variables, locals, modules, output
+	m := testModule(t, "eval-context-basic")
+	p := testProvider("test")
+	ctx := testContext2(t, &ContextOpts{
+		Config: m,
+		Providers: map[addrs.Provider]providers.Factory{
+			addrs.NewDefaultProvider("test"): testProviderFuncFixed(p),
+		},
+	})
+
+	scope, diags := ctx.Eval(addrs.RootModuleInstance)
+	if diags.HasErrors() {
+		t.Fatalf("Eval errors: %s", diags.Err())
+	}
+
+	// Since we're testing 'eval' (used by terraform console), impure functions
+	// should be allowed by the scope.
+	if scope.PureOnly == true {
+		t.Fatal("wrong result: eval should allow impure funcs")
+	}
+
+	for _, test := range tests {
+		t.Run(test.Input, func(t *testing.T) {
+			// Parse the test input as an expression
+			expr, _ := hclsyntax.ParseExpression([]byte(test.Input), "<test-input>", hcl.Pos{Line: 1, Column: 1})
+			got, diags := scope.EvalExpr(expr, cty.DynamicPseudoType)
+
+			if diags.HasErrors() {
+				t.Fatalf("unexpected error: %s", diags.Err())
+			}
+
+			if !test.ImpureFunc {
+				if !got.RawEquals(test.Want) {
+					t.Fatalf("wrong result: want %#v, got %#v", test.Want, got)
+				}
+			}
+		})
+	}
+}

terraform/evaluate.go

@@ -71,7 +71,7 @@ func (e *Evaluator) Scope(data lang.Data, self addrs.Referenceable) *lang.Scope
 	return &lang.Scope{
 		Data:     data,
 		SelfAddr: self,
-		PureOnly: e.Operation != walkApply && e.Operation != walkDestroy,
+		PureOnly: e.Operation != walkApply && e.Operation != walkDestroy && e.Operation != walkEval,
 		BaseDir:  ".", // Always current working directory for now.
 	}
 }

terraform/testdata/eval-context-basic/child/main.tf

@@ -0,0 +1,7 @@
+variable "list" {
+}
+
+
+output "result" {
+  value = length(var.list)
+}

terraform/testdata/eval-context-basic/main.tf

@@ -0,0 +1,39 @@
+variable "number" {
+  default = 3
+}
+
+variable "string" {
+  default = "Hello, World"
+}
+
+variable "map" {
+  type = map(string)
+  default = {
+    "foo" = "bar",
+    "baz" = "bat",
+  }
+}
+
+locals {
+  result = length(var.list)
+}
+
+variable "list" {
+  type    = list(string)
+  default = ["red", "orange", "yellow", "green", "blue", "purple"]
+}
+
+resource "test_resource" "example" {
+  for_each = var.map
+  name     = each.key
+  tag      = each.value
+}
+
+module "child" {
+  source = "./child"
+  list   = var.list
+}
+
+output "result" {
+  value = module.child.result
+}