Migrate to Jest and Make Use of Snapshot Testing

package.json

@@ -47,12 +47,16 @@
     "@commitlint/travis-cli": "^6.1.3",
     "@semantic-release/apm-config": "^2.0.1",
     "@types/atom": "^1.25.1",
+    "@types/jest": "^22.2.3",
     "@types/node": "^9.6.5",
+    "atom-test-runner-jest": "^0.2.0",
     "husky": "^0.14.3",
+    "jest-preset-atom": "^0.2.1",
     "semantic-release": "^15.1.7"
   },
   "scripts": {
-    "commitmsg": "commitlint -e $GIT_PARAMS"
+    "commitmsg": "commitlint -e $GIT_PARAMS",
+    "test": "atom --test spec"
   },
   "atomTranspilers": [
     {
@@ -81,5 +85,9 @@
       "title": "The Path to SwiftLint",
       "default": "/usr/local/bin/swiftlint"
     }
+  },
+  "atomTestRunner": "atom-test-runner-jest",
+  "jest": {
+    "preset": "jest-preset-atom"
   }
 }

spec/__snapshots__/linter-swiftlint-spec.ts.snap

@@ -0,0 +1,25 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`The swiftlint provider for Linter finds nothing wrong with a well formed file 1`] = `Array []`;
+
+exports[`The swiftlint provider for Linter finds something wrong with a not well formed file 1`] = `
+Array [
+  Object {
+    "excerpt": "Identifier Name Violation: Variable name should be between 3 and 40 characters long: 's' (identifier_name)",
+    "location": Object {
+      "file": "../fixtures/not-well-formed.swift",
+      "position": Array [
+        Array [
+          2,
+          0,
+        ],
+        Array [
+          2,
+          3,
+        ],
+      ],
+    },
+    "severity": "error",
+  },
+]
+`;

spec/linter-swiftlint-spec.ts

@@ -0,0 +1,46 @@
+import * as path from "path";
+
+// Make files in Linter results relative, so that they are consistent across environments.
+expect.addSnapshotSerializer({
+  test: val => val && val.hasOwnProperty("file") && path.isAbsolute(val.file),
+  print: (val, serialize) => {
+    return serialize({
+      ...val,
+      file: path.relative(__filename, val.file)
+    });
+  }
+});
+
+describe("The swiftlint provider for Linter", () => {
+  const { lint } = require("../src/index").provideLinter();
+
+  beforeEach(async () => {
+    await atom.packages.activatePackage("linter-swiftlint");
+  });
+
+  it("should be in the packages list", () => {
+    expect(atom.packages.isPackageLoaded("linter-swiftlint")).toBe(true);
+  });
+
+  it("should be an active package", () => {
+    expect(atom.packages.isPackageActive("linter-swiftlint")).toBe(true);
+  });
+
+  it("finds nothing wrong with a well formed file", async () => {
+    const editor = await atom.workspace.open(
+      __dirname + "/fixtures/well-formed.swift"
+    );
+    const messages = await lint(editor);
+
+    expect(messages).toMatchSnapshot();
+  });
+
+  it("finds something wrong with a not well formed file", async () => {
+    const editor = await atom.workspace.open(
+      __dirname + "/fixtures/not-well-formed.swift"
+    );
+    const messages = await lint(editor);
+
+    expect(messages).toMatchSnapshot();
+  });
+});