[eas-build-job] Add local composite function schema

packages/eas-build-job/src/__tests__/compositeFunction.test.ts

@@ -0,0 +1,78 @@
+import { ZodError } from 'zod';
+
+import { CompositeFunctionConfigZ } from '../compositeFunction';
+
+describe('CompositeFunctionConfigZ', () => {
+  it('accepts a valid local composite function config', () => {
+    const config = {
+      name: 'Setup',
+      inputs: [{ name: 'greeting', type: 'string', default_value: 'hello' }],
+      outputs: { version: { value: '${{ steps.read.outputs.version }}' } },
+      runs: {
+        steps: [{ id: 'read', run: 'set-output version "1.0.0"' }],
+      },
+    };
+    expect(CompositeFunctionConfigZ.parse(config)).toEqual(config);
+  });
+
+  it('accepts shorthand input names', () => {
+    const config = {
+      inputs: ['greeting'],
+      runs: {
+        steps: [{ run: 'echo hello' }],
+      },
+    };
+    expect(CompositeFunctionConfigZ.parse(config)).toEqual(config);
+  });
+
+  it('accepts a minimal config with only runs.steps', () => {
+    const config = {
+      runs: {
+        steps: [{ run: 'echo hello' }],
+      },
+    };
+    expect(CompositeFunctionConfigZ.parse(config)).toEqual(config);
+  });
+
+  it('applies default input type "string" when omitted', () => {
+    const config = {
+      inputs: [{ name: 'greeting' }],
+      runs: {
+        steps: [{ run: 'echo hello' }],
+      },
+    };
+    expect(CompositeFunctionConfigZ.parse(config)).toEqual({
+      inputs: [{ name: 'greeting', type: 'string' }],
+      runs: {
+        steps: [{ run: 'echo hello' }],
+      },
+    });
+  });
+
+  it('rejects unknown top-level keys', () => {
+    const config = {
+      unknown_field: true,
+      runs: {
+        steps: [{ run: 'echo hello' }],
+      },
+    };
+    expect(() => CompositeFunctionConfigZ.parse(config)).toThrow(ZodError);
+    expect(() => CompositeFunctionConfigZ.parse(config)).toThrow(/unknown_field/);
+  });
+
+  it('errors when runs.steps is empty', () => {
+    const config = {
+      name: 'Broken',
+      runs: { steps: [] },
+    };
+    expect(() => CompositeFunctionConfigZ.parse(config)).toThrow(ZodError);
+    try {
+      CompositeFunctionConfigZ.parse(config);
+    } catch (err) {
+      expect(err).toBeInstanceOf(ZodError);
+      expect((err as ZodError).issues[0]?.message).toMatch(
+        /must declare at least one step under "runs.steps"/
+      );
+    }
+  });
+});

packages/eas-build-job/src/compositeFunction.ts

@@ -0,0 +1,114 @@
+/**
+ * Schema for local composite functions, reusable step groups referenced via `uses:` in EAS
+ * workflows (`.eas/workflows/*.yml`) or inline job step definitions.
+ *
+ * This module defines the shape of a composite function configuration file (`function.yml`).
+ * Callers that load composite function files format validation errors from `CompositeFunctionConfigZ`.
+ * Local composite functions are not supported in `.eas/build/*.yml` custom build config files.
+ */
+import { z } from 'zod';
+
+import { StepZ } from './step';
+
+const CompositeFunctionInputValueTypeNameZ = z.enum(['string', 'boolean', 'number', 'json']);
+
+const CompositeFunctionInputValueZ = z.union([
+  z.string(),
+  z.boolean(),
+  z.number(),
+  z.array(z.unknown()),
+  z.record(z.string(), z.unknown()),
+]);
+
+const CompositeFunctionInputZ = z.union([
+  z
+    .string()
+    .describe('Shorthand for an input name with default type "string" and no default value.'),
+  z
+    .object({
+      name: z.string(),
+      type: CompositeFunctionInputValueTypeNameZ.default('string'),
+      default_value: CompositeFunctionInputValueZ.optional(),
+      allowed_values: z.array(CompositeFunctionInputValueZ).optional(),
+      required: z.boolean().optional(),
+    })
+    .strict(),
+]);
+
+const CompositeFunctionOutputZ = z
+  .object({
+    description: z.string().optional(),
+    /**
+     * @example
+     * value: '${{ steps.read.outputs.version }}'
+     */
+    value: z.string().describe('Expression that resolves to the output value.'),
+  })
+  .strict();
+
+export const CompositeFunctionConfigZ = z
+  .object({
+    /**
+     * @example
+     * name: Setup
+     */
+    name: z.string().optional().describe('Display name of the composite function.'),
+    description: z.string().optional(),
+    /**
+     * @example
+     * inputs:
+     *   - greeting
+     *   - name: platform
+     *     type: string
+     *     default_value: ios
+     */
+    inputs: z
+      .array(CompositeFunctionInputZ)
+      .optional()
+      .describe('Inputs accepted by the composite function.'),
+    /**
+     * @example
+     * outputs:
+     *   version:
+     *     value: '${{ steps.read.outputs.version }}'
+     */
+    outputs: z
+      .record(z.string(), CompositeFunctionOutputZ)
+      .optional()
+      .describe('Named outputs exposed by the composite function to its caller.'),
+    runs: z.object({
+      /**
+       * @example
+       * runs:
+       *   steps:
+       *     - id: read
+       *       run: set-output version "1.0.0"
+       */
+      steps: z
+        .array(StepZ)
+        .min(1, {
+          message: 'A composite function must declare at least one step under "runs.steps".',
+        })
+        .describe('Steps executed when the composite function is invoked.'),
+    }),
+  })
+  .strict();
+
+/**
+ * Structure of a local composite function configuration file (`function.yml`).
+ *
+ * @example
+ * name: Setup
+ * inputs:
+ *   - greeting
+ * outputs:
+ *   version:
+ *     value: '${{ steps.read.outputs.version }}'
+ * runs:
+ *   steps:
+ *     - id: read
+ *       run: set-output version "1.0.0"
+ */
+export type CompositeFunctionConfig = z.infer<typeof CompositeFunctionConfigZ>;
+
+export type CompositeFunctionCatalog = Record<string, CompositeFunctionConfig>;

packages/eas-build-job/src/index.ts

@@ -26,6 +26,7 @@ export * from './context';
 export * from './generic';
 export * from './hooks';
 export * from './step';
+export * from './compositeFunction';
 export * from './submission-config';
 export * from './projectPackage';