From f8978632889457546de90c6c45e96a1a654ac4cf Mon Sep 17 00:00:00 2001
From: Martin Atkins <mart@degeneration.co.uk>
Date: Thu, 7 May 2020 10:48:45 -0700
Subject: [PATCH] providers/terraform: test that validation does not configure
 backend

---
 .../providers/terraform/data_source_state.go  | 16 ++++-
 .../terraform/data_source_state_test.go       | 65 +++++++++++++++++++
 2 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/builtin/providers/terraform/data_source_state.go b/builtin/providers/terraform/data_source_state.go
index d245954f40..f73a0a2313 100644
--- a/builtin/providers/terraform/data_source_state.go
+++ b/builtin/providers/terraform/data_source_state.go
@@ -171,7 +171,7 @@ func getBackend(cfg cty.Value) (backend.Backend, cty.Value, tfdiags.Diagnostics)
 
 	// Create the client to access our remote state
 	log.Printf("[DEBUG] Initializing remote state backend: %s", backendType)
-	f := backendInit.Backend(backendType)
+	f := getBackendFactory(backendType)
 	if f == nil {
 		diags = diags.Append(tfdiags.AttributeValue(
 			tfdiags.Error,
@@ -216,3 +216,17 @@ func getBackend(cfg cty.Value) (backend.Backend, cty.Value, tfdiags.Diagnostics)
 
 	return b, newVal, diags
 }
+
+// overrideBackendFactories allows test cases to control the set of available
+// backends to allow for more self-contained tests. This should never be set
+// in non-test code.
+var overrideBackendFactories map[string]backend.InitFn
+
+func getBackendFactory(backendType string) backend.InitFn {
+	if len(overrideBackendFactories) > 0 {
+		// Tests may override the set of backend factories.
+		return overrideBackendFactories[backendType]
+	}
+
+	return backendInit.Backend(backendType)
+}
diff --git a/builtin/providers/terraform/data_source_state_test.go b/builtin/providers/terraform/data_source_state_test.go
index 7123ef1ed0..fca8c98349 100644
--- a/builtin/providers/terraform/data_source_state_test.go
+++ b/builtin/providers/terraform/data_source_state_test.go
@@ -1,10 +1,14 @@
 package terraform
 
 import (
+	"fmt"
+	"log"
 	"testing"
 
 	"github.com/apparentlymart/go-dump/dump"
 	"github.com/hashicorp/terraform/backend"
+	"github.com/hashicorp/terraform/configs/configschema"
+	"github.com/hashicorp/terraform/states/statemgr"
 	"github.com/hashicorp/terraform/tfdiags"
 	"github.com/zclconf/go-cty/cty"
 )
@@ -283,3 +287,64 @@ func TestState_basic(t *testing.T) {
 		})
 	}
 }
+
+func TestState_validation(t *testing.T) {
+	// The main test TestState_basic covers both validation and reading of
+	// state snapshots, so this additional test is here only to verify that
+	// the validation step in isolation does not attempt to configure
+	// the backend.
+	overrideBackendFactories = map[string]backend.InitFn{
+		"failsconfigure": func() backend.Backend {
+			return backendFailsConfigure{}
+		},
+	}
+	defer func() {
+		// undo our overrides so we won't affect other tests
+		overrideBackendFactories = nil
+	}()
+
+	schema := dataSourceRemoteStateGetSchema().Block
+	config, err := schema.CoerceValue(cty.ObjectVal(map[string]cty.Value{
+		"backend": cty.StringVal("failsconfigure"),
+		"config":  cty.EmptyObjectVal,
+	}))
+	if err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+
+	diags := dataSourceRemoteStateValidate(config)
+	if diags.HasErrors() {
+		t.Fatalf("unexpected errors\n%s", diags.Err().Error())
+	}
+}
+
+type backendFailsConfigure struct{}
+
+func (b backendFailsConfigure) ConfigSchema() *configschema.Block {
+	log.Printf("[TRACE] backendFailsConfigure.ConfigSchema")
+	return &configschema.Block{} // intentionally empty configuration schema
+}
+
+func (b backendFailsConfigure) PrepareConfig(given cty.Value) (cty.Value, tfdiags.Diagnostics) {
+	// No special actions to take here
+	return given, nil
+}
+
+func (b backendFailsConfigure) Configure(config cty.Value) tfdiags.Diagnostics {
+	log.Printf("[TRACE] backendFailsConfigure.Configure(%#v)", config)
+	var diags tfdiags.Diagnostics
+	diags = diags.Append(fmt.Errorf("Configure should never be called"))
+	return diags
+}
+
+func (b backendFailsConfigure) StateMgr(workspace string) (statemgr.Full, error) {
+	return nil, fmt.Errorf("StateMgr not implemented")
+}
+
+func (b backendFailsConfigure) DeleteWorkspace(name string) error {
+	return fmt.Errorf("DeleteWorkspace not implemented")
+}
+
+func (b backendFailsConfigure) Workspaces() ([]string, error) {
+	return nil, fmt.Errorf("Workspaces not implemented")
+}