test: add test for failing command

package.json

@@ -27,6 +27,7 @@
     "babel-preset-stage-0": "^6.24.1",
     "codecov": "^2.2.0",
     "if-env": "^1.0.0",
+    "invert-promise": "^1.0.1",
     "jest": "^20.0.0",
     "mock-bin": "^2.0.0",
     "mock-git": "^2.0.0",

src/__tests__/__snapshots__/index.test.js.snap

@@ -2,6 +2,8 @@
 
 exports[`git-exec-and-restage no command, no args and no files staged 1`] = `[Error: Usage: git-exec-and-restage <command> [...command-args --] [...files]]`;
 
+exports[`git-exec-and-restage throws when command fails 1`] = `"Error running command: Exited with status 1"`;
+
 exports[`git-exec-and-restage with command and arguments, no files 1`] = `
 Array [
   "git diff-index --cached --name-only --diff-filter=ACDMRTUXB HEAD --",

src/__tests__/index.test.js

@@ -1,6 +1,7 @@
 import gitExecAndRestage from "../";
 import TestEnvironment from "TestEnvironment";
 import path from "path";
+import flip from "invert-promise";
 
 describe("git-exec-and-restage", () => {
   const env = new TestEnvironment();
@@ -14,6 +15,12 @@ describe("git-exec-and-restage", () => {
     await gitExecAndRestage(["prettier"]);
     expect(await env.log).toMatchSnapshot();
   });
+  it("throws when command fails", async () => {
+    await env.mockBinError("prettier");
+    const error = await flip(gitExecAndRestage(["prettier"]));
+    expect(error.__isExpectedError).toBe(true);
+    expect(error.message).toMatchSnapshot();
+  });
   it("with command and arguments, no files", async () => {
     await env.mockBin("prettier");
     await gitExecAndRestage(["prettier", "--write", "--"]);

yarn.lock

@@ -1559,6 +1559,10 @@ invert-kv@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/invert-kv/-/invert-kv-1.0.0.tgz#104a8e4aaca6d3d8cd157a8ef8bfab2d7a3ffdb6"
 
+invert-promise@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/invert-promise/-/invert-promise-1.0.1.tgz#22d8b5f3cef87633743f86a96b3885dcdfd91fa2"
+
 is-arrayish@^0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/is-arrayish/-/is-arrayish-0.2.1.tgz#77c99840527aa8ecb1a8ba697b80645a7a926a9d"