Expose hasEnv API now that getEnv can throw

spec/api.spec.ts

@@ -1,7 +1,7 @@
 import type { IsExact } from "conditional-type-checks";
 import { assert } from "conditional-type-checks";
 import type { SnapshotOut } from "../src";
-import { isReadOnlyNode, resolveIdentifier, types } from "../src";
+import { hasEnv, isReadOnlyNode, resolveIdentifier, types } from "../src";
 import {
   applySnapshot,
   getEnv,
@@ -15,7 +15,7 @@ import {
   isRoot,
 } from "../src/api";
 import { NamedThingClass, TestClassModel } from "./fixtures/TestClassModel";
-import { NamedThing, TestModel, TestModelSnapshot } from "./fixtures/TestModel";
+import { TestModel, TestModelSnapshot } from "./fixtures/TestModel";
 
 describe("getParent", () => {
   test("returns the proper root for a read-only instance", () => {
@@ -80,6 +80,28 @@ describe("getRoot", () => {
   });
 });
 
+describe("hasEnv", () => {
+  describe.each(["with", "without"])("%s an env", (withOrWithoutYou) => {
+    const expected = withOrWithoutYou == "with" ? true : false;
+    const env = withOrWithoutYou == "with" ? { test: 1 } : undefined;
+
+    test(`returns ${expected} for quick tree instances`, () => {
+      const m = TestModel.createReadOnly(TestModelSnapshot, env);
+      expect(hasEnv(m)).toEqual(expected);
+    });
+
+    test(`returns ${expected} for MST instances with an env`, () => {
+      const m = TestModel.create(TestModelSnapshot, env);
+      expect(hasEnv(m)).toEqual(expected);
+    });
+
+    test(`returns ${expected} for read only model class instances`, () => {
+      const m = TestClassModel.createReadOnly(TestModelSnapshot, env);
+      expect(hasEnv(m)).toEqual(expected);
+    });
+  });
+});
+
 describe("getEnv", () => {
   test("returns expected env for quick tree instances", () => {
     const m = TestModel.createReadOnly(TestModelSnapshot, { test: 1 });
@@ -92,6 +114,21 @@ describe("getEnv", () => {
     expect(getEnv(m)).toEqual({ test: 1 });
   });
 
+  test("returns expected env for read only model class instances", () => {
+    const m = TestClassModel.createReadOnly(TestModelSnapshot);
+    expect(() => getEnv(m)).toThrow();
+  });
+
+  test("returns expected env for quick tree instances", () => {
+    const m = TestModel.createReadOnly(TestModelSnapshot);
+    expect(() => getEnv(m)).toThrow();
+  });
+
+  test("returns expected env for MST instances", () => {
+    const m = TestModel.create(TestModelSnapshot);
+    expect(() => getEnv(m)).toThrow();
+  });
+
   test("returns expected env for read only model class instances", () => {
     const m = TestClassModel.createReadOnly(TestModelSnapshot, { test: 1 });
     expect(getEnv(m)).toEqual({ test: 1 });

src/api.ts

@@ -13,6 +13,7 @@ import {
   getParentOfType as mstGetParentOfType,
   getRoot as mstGetRoot,
   getType as mstGetType,
+  hasEnv as mstHasEnv,
   isArrayType as mstIsArrayType,
   isIdentifierType as mstIsIdentifierType,
   isMapType as mstIsMapType,
@@ -40,8 +41,8 @@ import type {
   IStateTreeNode,
   IType,
   Instance,
-  TreeContext,
   SnapshotIn,
+  TreeContext,
 } from "./types";
 
 export {
@@ -50,13 +51,13 @@ export {
   applyPatch,
   clone,
   createActionTrackingMiddleware2,
-  getRunningActionContext,
   destroy,
   detach,
   escapeJsonPath,
   getIdentifier,
   getPath,
   getPathParts,
+  getRunningActionContext,
   hasParent,
   isActionContextThisOrChildOf,
   isAlive,
@@ -178,7 +179,20 @@ export function getEnv<Env = any>(value: IAnyStateTreeNode): Env {
     return mstGetEnv(value);
   }
 
-  return (getContext(value)?.env ?? {}) as Env;
+  const env = getContext(value)?.env;
+  if (!env) {
+    throw new Error(`Failed to find the environment of ${value}`);
+  }
+
+  return env as Env;
+}
+
+export function hasEnv(value: IAnyStateTreeNode): boolean {
+  if (mstIsStateTreeNode(value)) {
+    return mstHasEnv(value);
+  }
+
+  return !!getContext(value)?.env;
 }
 
 export const getRoot = <T extends IAnyType>(value: IAnyStateTreeNode): Instance<T> => {