chore: add parseExpect() util function

package.json

@@ -41,6 +41,8 @@
     "eslint-plugin-eslint-plugin": "^1.4.0",
     "eslint-plugin-node": "^6.0.0",
     "eslint-plugin-prettier": "^2.3.1",
+    "espree": "^3.5.4",
+    "estraverse": "^4.2.0",
     "husky": "^0.14.3",
     "jest": "^22.0.4",
     "jest-runner-eslint": "^0.4.0",

rules/__tests__/parse-expect.test.js

@@ -0,0 +1,114 @@
+'use strict';
+
+const espree = require('espree');
+const estraverse = require('estraverse');
+const parseExpect = require('../parse-expect');
+
+const CASES = {
+  notExpect(parsed) {
+    expect(parsed).toBeNull();
+  },
+  'expect()'(parsed) {
+    expect(parsed).toMatchObject({
+      arguments: [],
+      properties: [],
+      matcher: undefined,
+      matcherArguments: [],
+    });
+  },
+  'expect().toBe'(parsed) {
+    expect(parsed).toMatchObject({
+      arguments: [],
+      properties: [Identifier('toBe')],
+      matcher: undefined,
+      matcherArguments: [],
+    });
+  },
+  'expect().toBe()'(parsed) {
+    expect(parsed).toMatchObject({
+      arguments: [],
+      properties: [],
+      matcher: Identifier('toBe'),
+      matcherArguments: [],
+    });
+  },
+  'expect(Promise.resolve(2)).not.resolves.toEqual(3)'(parsed) {
+    expect(parsed).toMatchObject({
+      arguments: [
+        CallExpression(Identifier('Promise'), Identifier('resolve'), [
+          Literal(2),
+        ]),
+      ],
+      properties: [Identifier('not'), Identifier('resolves')],
+      matcher: Identifier('toEqual'),
+      matcherArguments: [Literal(3)],
+    });
+  },
+  'expect().a.b.c.d.e.f()'(parsed) {
+    expect(parsed).toMatchObject({
+      arguments: [],
+      properties: [
+        Identifier('a'),
+        Identifier('b'),
+        Identifier('c'),
+        Identifier('d'),
+        Identifier('e'),
+      ],
+      matcher: Identifier('f'),
+      matcherArguments: [],
+    });
+  },
+};
+
+Object.keys(CASES).forEach(code => {
+  test(code, () => {
+    const assertion = CASES[code];
+    const node = findExpect(code);
+    assertion(parseExpect(node));
+  });
+});
+
+function findExpect(code) {
+  let callExpression = null;
+
+  const ast = espree.parse(code);
+  estraverse.traverse(ast, {
+    enter(node, parent) {
+      node.parent = parent;
+      if (
+        !callExpression &&
+        node.type === 'CallExpression' &&
+        node.callee.name === 'expect'
+      ) {
+        callExpression = node;
+      }
+    },
+  });
+
+  return callExpression;
+}
+
+function Identifier(name) {
+  return {
+    type: 'Identifier',
+    name,
+  };
+}
+
+function Literal(value) {
+  return {
+    type: 'Literal',
+    value,
+  };
+}
+
+function CallExpression(object, property, args) {
+  return {
+    type: 'CallExpression',
+    callee: {
+      object,
+      property,
+    },
+    arguments: args || [],
+  };
+}

rules/parse-expect.js

@@ -0,0 +1,35 @@
+'use strict';
+
+module.exports = function parseExpect(node) {
+  if (node && node.type === 'CallExpression' && node.callee.name === 'expect') {
+    const properties = [];
+    let matcherArguments = [];
+    let matcher = undefined;
+    let parent = node.parent;
+    while (parent) {
+      if (parent.type === 'MemberExpression') {
+        const grandParentType = parent.parent && parent.parent.type;
+        switch (grandParentType) {
+          case 'CallExpression': {
+            matcher = parent.property;
+            matcherArguments = matcherArguments.concat(parent.parent.arguments);
+            break;
+          }
+          case 'MemberExpression':
+          case 'ExpressionStatement': {
+            properties.push(parent.property);
+            break;
+          }
+        }
+      }
+      parent = parent.parent;
+    }
+    return {
+      arguments: node.arguments,
+      properties,
+      matcher,
+      matcherArguments,
+    };
+  }
+  return null;
+};

yarn.lock

@@ -1873,7 +1873,7 @@ eslint@^4.10.0, eslint@^4.5.0:
     table "4.0.2"
     text-table "~0.2.0"
 
-espree@^3.5.2:
+espree@^3.5.2, espree@^3.5.4:
   version "3.5.4"
   resolved "https://registry.yarnpkg.com/espree/-/espree-3.5.4.tgz#b0f447187c8a8bed944b815a660bddf5deb5d1a7"
   dependencies: