Getting closer to a working rule to enforce that a relative import re…

…solves to an extant file.

.editorconfig

@@ -5,4 +5,5 @@ insert_final_newline = true
 
 [*.js]
 indent_style = space
-end_of_line = lf
+indent_size = 2
+end_of_line = lf

files/.eslintrc

@@ -0,0 +1,3 @@
+---
+  ecmaFeatures:
+    modules: true

files/bar.js

@@ -0,0 +1 @@
+export function foo() { return "foo"; }

files/foo.js

@@ -0,0 +1 @@
+import foo from './bar';

index.js

@@ -1,3 +1,4 @@
 exports.rules = {
-	"test-import-visitor": require("./lib/rules/test-import-visitor")
+	"test-import-visitor": require("./lib/rules/test-import-visitor"),
+  "valid-relative-path": require("./lib/rules/valid-relative-path")
 };

lib/rules/valid-relative-path.js

@@ -0,0 +1,31 @@
+/**
+ * @fileOverview Ensures that an imported relative path exists, relative to the currently linting file.
+ * @author Ben Mosher
+ */
+
+"use strict";
+
+var path = require("path");
+
+var RELATIVE_PATH = new RegExp("^(\.{1,2})?" + path.sep);
+
+function isRelative(p) {
+  return RELATIVE_PATH.test(p);
+}
+
+function resolveImportPath(context, importPath) {
+  return path.resolve(path.dirname(context.getFilename()), importPath);
+}
+
+module.exports = function (context) {
+  return {
+    "ImportDeclaration": function (node) {
+      var importPath = node.source.value;
+      if (isRelative(importPath)) {
+        context.report(node, resolveImportPath(context, importPath));
+      }
+
+      // check file exists
+    }
+  };
+};

package.json

@@ -26,8 +26,10 @@
   },
   "homepage": "https://github.com/benmosher/eslint-plugin-import",
   "devDependencies": {
-    "eslint": "^0.17.0",
+    "chai": "^2.1.2",
+    "eslint": "^0.16.x",
     "eslint-tester": "^0.6.0",
-    "mocha": "^2.2.1"
+    "mocha": "^2.2.1",
+    "object-assign": "^2.0.0"
   }
 }

tests/.eslintrc

@@ -0,0 +1,3 @@
+---
+  env:
+    mocha: true

tests/lib/rules/test-import-visitor.js

@@ -1,12 +1,13 @@
 "use strict";
 
 var linter = require("eslint").linter,
-    ESLintTester = require("eslint-tester"),
-    eslintTester = new ESLintTester(linter);
+    ESLintTester = require("eslint-tester");
+
+var eslintTester = new ESLintTester(linter);
 
 eslintTester.addRuleTest("lib/rules/test-import-visitor", {
   valid: [
-    "var validVariable = true;",
+    "var validVariable = true;"
   ],
 
   invalid: [
@@ -16,4 +17,4 @@ eslintTester.addRuleTest("lib/rules/test-import-visitor", {
       errors: [ { message: "This is an import!" } ]
     }
   ]
-});
+});

tests/lib/rules/valid-relative-path.js

@@ -0,0 +1,48 @@
+"use strict";
+
+var assign = require("object-assign");
+
+var expect = require("chai").expect;
+
+var path = require("path");
+
+var linter = require("eslint").linter,
+    CLIEngine = require("eslint").CLIEngine,
+    ESLintTester = require("eslint-tester");
+
+var eslintTester = new ESLintTester(linter);
+
+function valid(c) {
+  return {
+    code: c,
+    ecmaFeatures: { modules: true}
+  };
+}
+
+function invalid(c, errors) {
+  return assign(valid(c), {errors: errors});
+}
+
+eslintTester.addRuleTest("lib/rules/valid-relative-path", {
+  valid: [
+    valid("import foo from 'bar';")
+  ],
+
+  invalid: [
+    invalid("import foo from './bar/baz'",
+      [ { message: "<input>" } ])
+  ]
+});
+
+describe("valid-relative-path: against actual files", function () {
+  var cli = new CLIEngine({
+    rulePaths: [path.resolve(process.cwd(), "lib/rules")],
+    rules: { "valid-relative-path": 2 }
+  });
+
+  it("should follow relative paths.", function () {
+    var report = cli.executeOnFiles([path.join(__dirname, "../../../files/foo.js")]);
+    console.log(report.results[0].messages);
+    expect(report.errorCount).to.equal(1);
+  });
+});