From 7b766924ec5547344faba69b90026bbaacf401ce Mon Sep 17 00:00:00 2001
From: evanboyle <evan@pulumi.com>
Date: Thu, 8 Oct 2020 11:07:35 -0700
Subject: [PATCH] update error strategy to be more idiomatic

---
 sdk/nodejs/x/automation/cmd.ts    |  6 +--
 sdk/nodejs/x/automation/errors.ts | 75 +++++++++++++++++++------------
 sdk/nodejs/x/automation/stack.ts  |  4 +-
 3 files changed, 52 insertions(+), 33 deletions(-)

diff --git a/sdk/nodejs/x/automation/cmd.ts b/sdk/nodejs/x/automation/cmd.ts
index ce1b25256..a16cd8d88 100644
--- a/sdk/nodejs/x/automation/cmd.ts
+++ b/sdk/nodejs/x/automation/cmd.ts
@@ -14,7 +14,7 @@
 
 import * as childProcess from "child_process";
 
-import { CommandError } from "./errors";
+import { createCommandError } from "./errors";
 
 /** @internal */
 export class CommandResult {
@@ -73,13 +73,13 @@ export function runPulumiCmd(
             const resCode = code !== null ? code : unknownErrCode;
             const result = new CommandResult(stdout, stderr, resCode);
             if (code !== 0) {
-                return reject(new CommandError(result));
+                return reject(createCommandError(result));
             }
             return resolve(result);
         });
         proc.on("error", (err) => {
             const result = new CommandResult(stdout, stderr, unknownErrCode, err);
-            return reject(new CommandError(result));
+            return reject(createCommandError(result));
         });
     });
 }
diff --git a/sdk/nodejs/x/automation/errors.ts b/sdk/nodejs/x/automation/errors.ts
index 08ec7894e..0ba7a7185 100644
--- a/sdk/nodejs/x/automation/errors.ts
+++ b/sdk/nodejs/x/automation/errors.ts
@@ -16,9 +16,6 @@ import { CommandResult } from "./cmd";
 
 /**
  * CommandError is an error resulting from invocation of a Pulumi Command.
- * This is an opaque error that provides utility functions to detect specific error cases
- * such as concurrent stack updates (`isConcurrentUpdateError`). If you'd like to detect an additional
- * error case that isn't currently covered, please file an issue: https://github.com/pulumi/pulumi/issues/new
  * @alpha
  */
 export class CommandError extends Error {
@@ -27,30 +24,52 @@ export class CommandError extends Error {
         super(commandResult.toString());
         this.name = "CommandError";
     }
-    /**
-     * Returns true if the error was a result of a conflicting update locking the stack.
-     *
-     * @returns a boolean indicating if this failure was due to a conflicting concurrent update on the stack.
-     */
-    isConcurrentUpdateError() {
-        return this.commandResult.stderr.indexOf("[409] Conflict: Another update is currently in progress.") >= 0;
-    }
-    /**
-     * Returns true if the error was the result of selecting a stack that does not exist.
-     *
-     * @returns a boolean indicating if this failure was the result of selecting a stack that does not exist.
-     */
-    isSelectStack404Error() {
-        const exp = new RegExp("no stack named.*found");
-        return exp.test(this.commandResult.stderr);
-    }
-    /**
-     * Returns true if the error was a result of creating a stack that already exists.
-     *
-     * @returns a boolean indicating if the error was a result of creating a stack that already exists.
-     */
-    isCreateStack409Error() {
-        const exp = new RegExp("stack.*already exists");
-        return exp.test(this.commandResult.stderr);
+}
+
+/**
+ * ConcurrentUpdateError is thrown when attempting to update a stack that already has an update in progress.
+ */
+export class ConcurrentUpdateError extends CommandError {
+    /** @internal */
+    constructor(commandResult: CommandResult) {
+        super(commandResult);
+        this.name = "ConcurrentUpdateError";
     }
 }
+
+/**
+ * StackNotFoundError is thrown when attempting to select a stack that does not exist.
+ */
+export class StackNotFoundError extends CommandError {
+    /** @internal */
+    constructor(commandResult: CommandResult) {
+        super(commandResult);
+        this.name = "StackNotFoundError";
+    }
+}
+
+/**
+ * StackAlreadyExistsError is thrown when attempting to create a stack that already exists.
+ */
+export class StackAlreadyExistsError extends CommandError {
+    /** @internal */
+    constructor(commandResult: CommandResult) {
+        super(commandResult);
+        this.name = "StackAlreadyExistsError";
+    }
+}
+
+const notFoundRegex = new RegExp("no stack named.*found");
+const alreadyExistsRegex = new RegExp("stack.*already exists");
+const conflictText = "[409] Conflict: Another update is currently in progress.";
+
+/** @internal */
+export function createCommandError(result: CommandResult): CommandError {
+    const stderr = result.stderr;
+    return (
+        notFoundRegex.test(stderr) ? new StackNotFoundError(result) :
+        alreadyExistsRegex.test(stderr) ? new StackAlreadyExistsError(result) :
+        stderr.indexOf(conflictText) >= 0 ? new ConcurrentUpdateError(result) :
+        new CommandError(result)
+    );
+}
diff --git a/sdk/nodejs/x/automation/stack.ts b/sdk/nodejs/x/automation/stack.ts
index 5af1ee734..a4798a7b5 100644
--- a/sdk/nodejs/x/automation/stack.ts
+++ b/sdk/nodejs/x/automation/stack.ts
@@ -16,7 +16,7 @@ import * as grpc from "@grpc/grpc-js";
 
 import { CommandResult, runPulumiCmd } from "./cmd";
 import { ConfigMap, ConfigValue } from "./config";
-import { CommandError } from "./errors";
+import { StackAlreadyExistsError } from "./errors";
 import { LanguageServer, maxRPCMessageSize } from "./server";
 import { PulumiFn, Workspace } from "./workspace";
 
@@ -92,7 +92,7 @@ export class Stack {
                 return this;
             case "createOrSelect":
                 this.ready = workspace.createStack(name).catch((err) => {
-                    if (err instanceof CommandError && err.isCreateStack409Error()) {
+                    if (err instanceof StackAlreadyExistsError) {
                         return workspace.selectStack(name);
                     }
                     throw err;