first prototype

__tests__/assets/style.css

@@ -0,0 +1,5 @@
+a {
+  font-family: Roboto;
+  color: black;
+  font-size: 12px;
+}

__tests__/assets/test

@@ -0,0 +1 @@
+abc

__tests__/ast/ast.test.ts

@@ -0,0 +1,20 @@
+import postcss from 'postcss';
+import * as AST from "../../src/ast/ast";
+
+describe("Test ast functions", () => {
+  it("Should format postcss ast to new ast format", async () => {
+    const input = postcss.parse("a{font-size: 12px; color: red}");
+    const result = AST.format(input);
+    const expected = [
+      {
+        selector: "a",
+        props: [
+          {prop: "font-size", value: "12px"},
+          {prop: "color", value: "red"}
+        ]
+      }
+    ];
+
+    expect(result).toEqual(expected);
+  })
+})

__tests__/files/files.test.ts

@@ -0,0 +1,11 @@
+import * as files from "../../src/files/files";
+
+describe("Test files functions", () => {
+  it("Should get content of file", async () => {
+    const filePath = "./__tests__/assets/test";
+    const result = await files.getContent(filePath);
+    const expected = "abc"
+
+    expect(result).toEqual(expected);
+  })
+})

__tests__/index.test.ts

@@ -7,13 +7,17 @@ function run(input: string, output: string, opts: object) {
   return postcss([ removeDuplicateCSS(opts) ])
     .process(input)
     .then(result => {
-      expect(result.css).toEqual(output);
+      expect(result.css.replace(/\s/g,'')).toEqual(output);
       expect(result.warnings().length).toBe(0);
     });
 }
 
 describe("Test main functions", () => {
   it("Should remove duplicate css properties", () => {
-    return run('a{}', 'a{}', {});
+    return run(
+      'a{font-size: 12px; color: blue; font-family: Roboto}',
+      'a{color:blue}',
+      {target: "./__tests__/assets/style.css"}
+    );
   })
 })

package.json

@@ -2,7 +2,7 @@
   "name": "RemoveDuplicateCSS",
   "version": "1.0.0",
   "description": "",
-  "main": "index.js",
+  "main": "./dist/index.js",
   "scripts": {
     "build": "tsc",
     "test": "jest tests",
@@ -13,6 +13,7 @@
   "license": "ISC",
   "devDependencies": {
     "@types/jest": "^23.3.1",
+    "@types/node": "^10.5.5",
     "jest": "^23.4.2",
     "ts-jest": "^23.0.1",
     "typescript": "^3.0.1"

src/ast/ast.d.ts

@@ -0,0 +1,11 @@
+declare namespace AST {
+  interface Node {
+    selector: string,
+    props: NodeProps[]
+  }
+
+  interface NodeProps {
+    prop: string,
+    value: string
+  }
+}

src/ast/ast.ts

@@ -0,0 +1,10 @@
+/// <reference path="./ast.d.ts" />
+
+export function format(ast) : AST.Node[] {
+  return ast.nodes.map(({selector, nodes}) => {
+    return {
+      selector,
+      props: nodes.map(({prop, value}) => ({prop, value}))
+    }
+  });
+}

src/files/files.ts

@@ -0,0 +1,13 @@
+import fs from "fs";
+
+export function getContent(path: string): Promise<string> {
+  return new Promise((resolve, reject) => {
+    fs.readFile(path, 'utf8', (err, file) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(file);
+      }
+    });
+  })
+}

src/index.ts

@@ -1,11 +1,32 @@
-"use strict";
-
 import postcss from "postcss";
+import * as AST from "./ast/ast";
+import * as files from "./files/files";
 
 export default postcss.plugin('RemoveDuplicateCSS', (opts) => {
+  return async (root, result) => {
+    try {
+      const cssContent = await files.getContent(opts.target);
+      const cssAst = postcss.parse(cssContent);
+      const newAst = AST.format(cssAst);
 
+      root.walkRules((rule) => {
+        const findedAst = newAst.find(ast => ast.selector === rule.selector);
 
-  return function (root, result) {
+        if (findedAst) {
+          rule.walkDecls(function(decl) {
+            if (findedAst.props.some(prop => prop.prop === decl.prop && prop.value === decl.value)) {
+              decl.remove();
+            }
+          });
 
+          if (!rule.nodes || !rule.nodes.length) {
+            rule.remove();
+          }
+        }
+      });
+    } catch (err) {
+      console.log("err", err);
+      console.error(err);
+    }
   };
 });