Extract machine context (#370)

* Parse machine context into an object * changeset * Parse -> Extract Co-authored-by: Mateusz Burzyński <[email protected]> * Use a special handler for parsing root state node to keep extracting context only in the root state node * Extract lazy context as expression string * Update packages/machine-extractor/src/__tests__/context.test.ts Co-authored-by: Mateusz Burzyński <[email protected]> * Update packages/machine-extractor/src/__tests__/context.test.ts Co-authored-by: Mateusz Burzyński <[email protected]> --------- Co-authored-by: Mateusz Burzyński <[email protected]>
statelyai · Sep 20, 2023 · d885182 · d885182
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diff --git a/.changeset/calm-balloons-ring.md b/.changeset/calm-balloons-ring.md
@@ -0,0 +1,5 @@
+---
+'@xstate/machine-extractor': minor
+---
+
+Extract machine context into an object
diff --git a/packages/machine-extractor/src/__tests__/context.test.ts b/packages/machine-extractor/src/__tests__/context.test.ts
@@ -0,0 +1,91 @@
+import { extractMachinesFromFile } from '..';
+
+describe('Context', () => {
+  it('Should be able to extract machine context into an object', () => {
+    const result = extractMachinesFromFile(`
+      createMachine({
+        context: {
+			str: 'some string',
+			num: 2,
+			bool: true,
+			arr: [1,2,3],
+			obj: {
+				str: 'some string',
+			num: 2,
+			bool: true,
+			arr: [1,2,3],
+			obj: {
+				a: 2
+			}
+			}
+		}
+      })
+    `);
+
+    expect(result?.machines[0]?.toConfig()).toMatchInlineSnapshot(`
+      {
+        "context": {
+          "arr": [
+            1,
+            2,
+            3,
+          ],
+          "bool": true,
+          "num": 2,
+          "obj": {
+            "arr": [
+              1,
+              2,
+              3,
+            ],
+            "bool": true,
+            "num": 2,
+            "obj": {
+              "a": 2,
+            },
+            "str": "some string",
+          },
+          "str": "some string",
+        },
+      }
+    `);
+  });
+
+  it('Should only account for context on the root node', () => {
+    const result = extractMachinesFromFile(`
+      createMachine({
+        initial: 'a',
+		states: {
+			a: {
+				context: {
+					foo: 'bar'
+				}
+			}
+		}
+      })
+    `);
+
+    expect(result?.machines[0]?.toConfig()).toMatchInlineSnapshot(`
+      {
+        "initial": "a",
+        "states": {
+          "a": {},
+        },
+      }
+    `);
+  });
+
+  it('Should extract lazy context as an expression string', () => {
+    const result = extractMachinesFromFile(`
+      createMachine({
+        context: () => ({})
+      })
+    `);
+
+    expect(result?.machines[0]?.toConfig()).toMatchInlineSnapshot(`
+      {
+        "context": "{{() => ({})}}",
+      }
+    `);
+  });
+});
diff --git a/packages/machine-extractor/src/toMachineConfig.ts b/packages/machine-extractor/src/toMachineConfig.ts
@@ -173,12 +173,33 @@ const parseStateNode = (
   return config;
 };
 
+const parseRootStateNode = (
+  astResult: StateNodeReturn,
+  opts: ToMachineConfigOptions | undefined,
+): ExtractorStateNodeConfig => {
+  const config: ExtractorMachineConfig = parseStateNode(astResult, opts);
+  if (t.isObjectExpression(astResult.context?.node)) {
+    config.context = extractObjectRecursively(
+      astResult.context!.node,
+      opts!.fileContent,
+    );
+  } else if (astResult.context) {
+    config.context = toJsonExpressionString(
+      opts!.fileContent.slice(
+        astResult.context.node.start!,
+        astResult.context.node.end!,
+      ),
+    );
+  }
+  return config;
+};
+
 export const toMachineConfig = (
   result: TMachineCallExpression,
   opts?: ToMachineConfigOptions,
 ): ExtractorMachineConfig | undefined => {
   if (!result?.definition) return undefined;
-  return parseStateNode(result?.definition, opts);
+  return parseRootStateNode(result?.definition, opts);
 };
 
 export const getActionConfig = (

diff --git a/packages/machine-extractor/src/types.ts b/packages/machine-extractor/src/types.ts
@@ -44,6 +44,7 @@ export type ExtractorStateNodeConfig = {
 export type ExtractorMachineConfig = ExtractorStateNodeConfig & {
   predictableActionArguments?: boolean;
   preserveActionOrder?: boolean;
+  context?: Record<string, any> | JsonExpressionString;
 };
 
 export type Location = t.SourceLocation | null;