test: Add a test that shows a custom workspace being baked-into a planfile

internal/command/plan_test.go

@@ -470,6 +470,79 @@ func TestPlan_outBackend(t *testing.T) {
 	}
 }
 
+// When using "-out" with a backend, the plan should encode the backend config
+// and also the selected workspace, if workspaces are supported by the backend.
+//
+// This test demonstrates that setting the workspace in the backend plan
+// responds to the selected workspace, versus other tests that show the same process
+// when defaulting to the default workspace when there's a lack of information about
+// the selected workspace.
+//
+// To test planning with a non-default workspace we need to use a backend that supports
+// workspaces. In this test the `inmem` backend is used.
+func TestPlan_outBackend_withWorkspace(t *testing.T) {
+	// Create a temporary working directory
+	td := t.TempDir()
+	testCopyDir(t, testFixturePath("plan-out-backend-workspace"), td)
+	t.Chdir(td)
+
+	// These values are coupled with the test fixture used above.
+	expectedBackendType := "inmem"
+	expectedWorkspace := "custom-workspace"
+
+	outPath := "foo"
+	p := testProvider()
+	p.GetProviderSchemaResponse = &providers.GetProviderSchemaResponse{
+		ResourceTypes: map[string]providers.Schema{
+			"test_instance": {
+				Body: &configschema.Block{
+					Attributes: map[string]*configschema.Attribute{
+						"id": {
+							Type:     cty.String,
+							Computed: true,
+						},
+						"ami": {
+							Type:     cty.String,
+							Optional: true,
+						},
+					},
+				},
+			},
+		},
+	}
+	p.PlanResourceChangeFn = func(req providers.PlanResourceChangeRequest) providers.PlanResourceChangeResponse {
+		return providers.PlanResourceChangeResponse{
+			PlannedState: req.ProposedNewState,
+		}
+	}
+	view, done := testView(t)
+	c := &PlanCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(p),
+			View:             view,
+		},
+	}
+
+	args := []string{
+		"-out", outPath,
+	}
+	code := c.Run(args)
+	output := done(t)
+	if code != 0 {
+		t.Logf("stdout: %s", output.Stdout())
+		t.Fatalf("plan command failed with exit code %d\n\n%s", code, output.Stderr())
+	}
+
+	plan := testReadPlan(t, outPath)
+
+	if got, want := plan.Backend.Type, expectedBackendType; got != want {
+		t.Errorf("wrong backend type %q; want %q", got, want)
+	}
+	if got, want := plan.Backend.Workspace, expectedWorkspace; got != want {
+		t.Errorf("wrong backend workspace %q; want %q", got, want)
+	}
+}
+
 func TestPlan_refreshFalse(t *testing.T) {
 	// Create a temporary working directory that is empty
 	td := t.TempDir()

internal/command/testdata/plan-out-backend-workspace/.terraform/README.md

@@ -0,0 +1,6 @@
+The test using this test fixture asserts that a plan generated from this configuration includes both:
+1. Details of the backend defined in the config when the plan was created
+2. Details of the workspace that was selected when the plan was generated
+
+The `inmem` backend is used because it supports the use of CE workspaces.
+We set a non-default workspace in `internal/command/testdata/plan-out-backend-workspace/.terraform/environment`.

internal/command/testdata/plan-out-backend-workspace/.terraform/environment

@@ -0,0 +1 @@
+custom-workspace

internal/command/testdata/plan-out-backend-workspace/.terraform/terraform.tfstate

@@ -0,0 +1,9 @@
+{
+    "version": 3,
+    "terraform_version": "1.15.0",
+    "backend": {
+        "type": "inmem",
+        "config": {},
+        "hash": 3307601501
+    }
+}

internal/command/testdata/plan-out-backend-workspace/main.tf

@@ -0,0 +1,8 @@
+terraform {
+  backend "inmem" {
+  }
+}
+
+resource "test_instance" "foo" {
+  ami = "bar"
+}