implement plan-diff command

cmd/terraform_commands.go

@@ -21,6 +21,11 @@ func getTerraformCommands() []*cobra.Command {
 				"nativeCommand": "true",
 			},
 		},
+		{
+			Use:   "plan-diff",
+			Short: "Compare two Terraform plans",
+			Long:  "Generate a visual diff between two Terraform plans. If the new plan is not provided, it will run 'terraform plan' to generate one.",
+		},
 		{
 			Use:   "apply",
 			Short: "Apply changes to infrastructure",
@@ -288,6 +293,10 @@ var commandMaps = map[string]func(cmd *cobra.Command){
 		cmd.PersistentFlags().Bool("from-plan", false, "If set atmos will use the previously generated plan file")
 		cmd.PersistentFlags().String("planfile", "", "Set the plan file to use")
 	},
+	"plan-diff": func(cmd *cobra.Command) {
+		cmd.PersistentFlags().String("orig", "", "Original Terraform plan file path")
+		cmd.PersistentFlags().String("new", "", "New Terraform plan file path (optional, if not provided, a new plan will be generated)")
+	},
 	"clean": func(cmd *cobra.Command) {
 		cmd.PersistentFlags().Bool("everything", false, "If set atmos will also delete the Terraform state files and directories for the component.")
 		cmd.PersistentFlags().Bool("force", false, "Forcefully delete Terraform state files and directories without interaction")

internal/exec/terraform.go

@@ -350,6 +350,13 @@
 			!u.SliceContainsStringHasPrefix(info.AdditionalArgsAndFlags, outFlag+"=") {
 			allArgsAndFlags = append(allArgsAndFlags, []string{outFlag, planFile}...)
 		}
+	case "plan-diff":
+		// The plan-diff command is handled separately
+		err = executeTerraformPlanDiff(atmosConfig, info, componentPath, varFile, planFile)
+		if err != nil {
+			return err
+		}
+		return nil
 	case "destroy":
 		allArgsAndFlags = append(allArgsAndFlags, []string{varFileFlag, varFile}...)
 	case "import":

internal/exec/terraform_plan_diff_test.go

@@ -0,0 +1,47 @@
+package exec
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/cloudposse/atmos/pkg/schema"
+)
+
+// TestPlanDiffCommandRouting tests that the plan-diff command is correctly routed
+// in the ExecuteTerraform function's switch statement.
+//
+// NOTE: This test will show a linter error when run separately with golangci-lint,
+// because ExecuteTerraform is defined in terraform.go and not visible when linting
+// this file alone. However, it works correctly when running 'go test' because
+// all files in the package are compiled together.
+func TestPlanDiffCommandRouting(t *testing.T) {
+	// Create minimal info with the plan-diff command
+	info := schema.ConfigAndStacksInfo{
+		Command:                "terraform",
+		SubCommand:             "plan-diff",
+		ComponentFromArg:       "test-component",
+		Component:              "test-component",
+		FinalComponent:         "test-component",
+		ComponentIsEnabled:     true,
+		AdditionalArgsAndFlags: []string{"--orig", "test.tfplan"},
+	}
+
+	// Execute the function - we expect it to fail because we haven't set up a proper environment
+	err := ExecuteTerraform(info) // This line will show a linter error but works in tests
+
+	// Verify we get an error since we have an incomplete setup
+	if err == nil {
+		t.Fatalf("Expected ExecuteTerraform to fail with incomplete setup")
+	}
+
+	// Check the error message to make sure it's not indicating that the command wasn't recognized
+	errMsg := err.Error()
+	t.Logf("Error: %v", errMsg)
+
+	// If the error indicates that the command wasn't recognized, the test should fail
+	if strings.Contains(errMsg, "unknown command") ||
+		strings.Contains(errMsg, "unrecognized command") ||
+		strings.Contains(errMsg, "invalid command") {
+		t.Errorf("Error suggests the plan-diff command wasn't recognized in the switch statement")
+	}
+}