Move validateExclusiveModes before getBody for fail-fast validation (#1663)

* Initial plan

* feat: refactor option validation to list-based approach and add delete+hide_and_recreate check

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* feat: add only_update to exclusive modes validation list

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* refactor: extract validation logic into src/validate.ts

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* refactor: move validateExclusiveModes before getBody in run()

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* test: assert getBody is not called when validateExclusiveModes fails

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

__tests__/validate.test.ts

@@ -0,0 +1,85 @@
+import {describe, expect, test} from "vitest"
+import {validateBody, validateExclusiveModes} from "../src/validate"
+
+describe("validateBody", () => {
+  test("throws when body is empty and neither delete nor hide is set", () => {
+    expect(() => validateBody("", false, false)).toThrow(
+      "Either message or path input is required",
+    )
+  })
+
+  test("does not throw when body is provided", () => {
+    expect(() => validateBody("some body", false, false)).not.toThrow()
+  })
+
+  test("does not throw when body is empty but deleteOldComment is true", () => {
+    expect(() => validateBody("", true, false)).not.toThrow()
+  })
+
+  test("does not throw when body is empty but hideOldComment is true", () => {
+    expect(() => validateBody("", false, true)).not.toThrow()
+  })
+})
+
+describe("validateExclusiveModes", () => {
+  test("does not throw when no modes are enabled", () => {
+    expect(() => validateExclusiveModes(false, false, false, false, false, false)).not.toThrow()
+  })
+
+  test("does not throw when exactly one mode is enabled", () => {
+    expect(() => validateExclusiveModes(true, false, false, false, false, false)).not.toThrow()
+    expect(() => validateExclusiveModes(false, true, false, false, false, false)).not.toThrow()
+    expect(() => validateExclusiveModes(false, false, true, false, false, false)).not.toThrow()
+    expect(() => validateExclusiveModes(false, false, false, true, false, false)).not.toThrow()
+    expect(() => validateExclusiveModes(false, false, false, false, true, false)).not.toThrow()
+    expect(() => validateExclusiveModes(false, false, false, false, false, true)).not.toThrow()
+  })
+
+  test("throws when delete and recreate are both true", () => {
+    expect(() => validateExclusiveModes(true, true, false, false, false, false)).toThrow(
+      "delete and recreate cannot be set to true simultaneously",
+    )
+  })
+
+  test("throws when delete and only_create are both true", () => {
+    expect(() => validateExclusiveModes(true, false, true, false, false, false)).toThrow(
+      "delete and only_create cannot be set to true simultaneously",
+    )
+  })
+
+  test("throws when delete and only_update are both true", () => {
+    expect(() => validateExclusiveModes(true, false, false, true, false, false)).toThrow(
+      "delete and only_update cannot be set to true simultaneously",
+    )
+  })
+
+  test("throws when delete and hide are both true", () => {
+    expect(() => validateExclusiveModes(true, false, false, false, true, false)).toThrow(
+      "delete and hide cannot be set to true simultaneously",
+    )
+  })
+
+  test("throws when delete and hide_and_recreate are both true", () => {
+    expect(() => validateExclusiveModes(true, false, false, false, false, true)).toThrow(
+      "delete and hide_and_recreate cannot be set to true simultaneously",
+    )
+  })
+
+  test("throws when only_create and only_update are both true", () => {
+    expect(() => validateExclusiveModes(false, false, true, true, false, false)).toThrow(
+      "only_create and only_update cannot be set to true simultaneously",
+    )
+  })
+
+  test("throws when hide and hide_and_recreate are both true", () => {
+    expect(() => validateExclusiveModes(false, false, false, false, true, true)).toThrow(
+      "hide and hide_and_recreate cannot be set to true simultaneously",
+    )
+  })
+
+  test("uses Oxford comma when three or more modes are enabled", () => {
+    expect(() => validateExclusiveModes(true, true, true, false, false, false)).toThrow(
+      "delete, recreate, and only_create cannot be set to true simultaneously",
+    )
+  })
+})