Docs/improve contributor onboarding (#4976)

* docs: add pre-push checklist to CONTRIBUTING.md

* docs: add CI badge and Developer Quick Start to README

* docs: create TESTING.md with block testing guide

* chore: add .nvmrc and fix .editorconfig indent

* chore: add lint checkbox to PR template and test issue template

* docs: address Walter's review feedback

- Add checkbox for duplicate PR check in test issue template
- Add license header example to TESTING.md template

Author: vyagh

.editorconfig

@@ -3,7 +3,7 @@ root = true
 [*]
 charset = utf-8
 indent_style = space
-indent_size = 2
+indent_size = 4
 end_of_line = lf
 insert_final_newline = true
 trim_trailing_whitespace = true

.github/ISSUE_TEMPLATE/test_contribution.md

@@ -0,0 +1,32 @@
+---
+name: 🧪 Test Contribution
+about: Add or improve unit tests
+title: ""
+labels: "testing"
+assignees: ""
+---
+
+### What needs testing
+
+<!-- Which file, block, or feature needs test coverage? -->
+
+### Current coverage
+
+<!-- If known, what's the current test coverage for this area? -->
+
+### Proposed approach
+
+<!-- How would you approach testing this? -->
+
+### Checklist
+
+-   [ ] I have read and followed the project's code of conduct.
+-   [ ] I have checked that no existing tests cover this area.
+-   [ ] I have checked that there is no open PR for the tests I am submitting.
+-   [ ] I have reviewed [docs/TESTING.md](docs/TESTING.md) for testing patterns.
+
+---
+
+📚 See [Testing Guide](docs/TESTING.md) for how to write block tests.
+
+🙋🏾🙋🏼 Questions: [Community Matrix Server](https://matrix.to/#/#sugar:matrix.org).

.github/PULL_REQUEST_TEMPLATE/generic.md

@@ -43,6 +43,7 @@ This PR fixes #
 -   [ ] I have added/updated tests that prove the effectiveness of these changes.
 -   [ ] I have updated the documentation to reflect these changes, if applicable.
 -   [ ] I have followed the project's coding style guidelines.
+-   [ ] I have run `npm run lint` and `npx prettier --check .` with no errors.
 -   [ ] I have addressed the code review feedback from the previous submission, if applicable.
 
 ## Additional Notes for Reviewers

.nvmrc

@@ -0,0 +1 @@
+20

CONTRIBUTING.md

@@ -53,6 +53,19 @@ following resources:
 Programmers, please follow these general [guidelines for
 contributions](https://github.com/sugarlabs/sugar-docs/blob/master/src/contributing.md).
 
+
+### Before You Push
+
+Run these commands locally before submitting a PR:
+
+```bash
+npm run lint              # ESLint
+npx prettier --check .    # Formatting
+npm test                  # Jest
+```
+
+If formatting fails, run `npx prettier --write .` to fix it.
+
 ### License Header
 
 Music Blocks is licensed under the [AGPL](https://www.gnu.org/licenses/agpl-3.0.en.html).

README.md

@@ -6,6 +6,10 @@
     <img src="https://img.shields.io/github/license/sugarlabs/musicblocks" />
 </a>
 
+<a href="https://github.com/sugarlabs/musicblocks/actions/workflows/node.js.yml" alt="CI">
+    <img src="https://github.com/sugarlabs/musicblocks/actions/workflows/node.js.yml/badge.svg" />
+</a>
+
 # Music Blocks
 
 “_All musicians are subconsciously mathematicians._” — Monk
@@ -217,6 +221,14 @@ provides a general overview of Sugar Lab's guidelines. See
 [Contributing](#CONTRIBUTING) section for specific details about this
 repository.
 
+### Developer Quick Start
+
+1. Clone and install: `git clone https://github.com/sugarlabs/musicblocks.git && npm install`
+2. Run locally: `npm run dev`
+3. Before pushing: `npm run lint && npx prettier --check . && npm test`
+
+For writing tests, see [docs/TESTING.md](./docs/TESTING.md).
+
 ## <a name="REPORTING_BUGS"></a>Reporting Bugs
 
 Bugs can be reported in the [issues

docs/TESTING.md

@@ -0,0 +1,141 @@
+# Testing Guide
+
+How to write unit tests for block files.
+
+## Running Tests
+
+```bash
+npm test                                    # Run all tests
+npm test -- path/to/file.test.js           # Run specific test file
+npm test -- --coverage                      # Run with coverage report
+```
+
+## Testing Blocks
+
+Block files (in `js/blocks/`) need specific mocks. Copy this template and modify for your block:
+
+### Basic Template
+
+Add a license header at the top of your test file:
+
+```javascript
+/**
+ * MusicBlocks v3.6.2
+ *
+ * @author Your Name
+ *
+ * @copyright 2026 Your Name
+ *
+ * @license
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ */
+```
+
+Then add the test code:
+
+```javascript
+const { setupYourBlocks } = jest.requireActual("../YourBlocks");
+
+global._ = s => s;
+global.NOINPUTERRORMSG = "NO_INPUT";
+
+class BaseBlock {
+    constructor(name) {
+        this.name = name;
+    }
+    setPalette(palette) {
+        this.palette = palette;
+    }
+    setHelpString(help) {
+        this.help = help;
+    }
+    formBlock(defn) {
+        this.formDefn = defn;
+    }
+    setup(activity) {
+        activity.registeredBlocks = activity.registeredBlocks || {};
+        activity.registeredBlocks[this.name] = this;
+        return this;
+    }
+}
+
+class FlowBlock extends BaseBlock {
+    constructor(name) {
+        super(name);
+    }
+    flow() {}
+}
+
+class ValueBlock extends BaseBlock {
+    constructor(name) {
+        super(name);
+    }
+    arg() {}
+}
+
+global.BaseBlock = BaseBlock;
+global.FlowBlock = FlowBlock;
+global.ValueBlock = ValueBlock;
+
+describe("YourBlocks", () => {
+    let activity;
+    let logo;
+
+    beforeEach(() => {
+        jest.clearAllMocks();
+
+        activity = {
+            registeredBlocks: {},
+            blocks: {
+                blockList: [],
+                palettes: { dict: {} }
+            },
+            turtles: {
+                ithTurtle: jest.fn(() => ({
+                    singer: { justCounting: [] }
+                }))
+            },
+            errorMsg: jest.fn()
+        };
+
+        logo = {
+            parseArg: jest.fn(),
+            runFromBlock: jest.fn()
+        };
+
+        setupYourBlocks(activity);
+    });
+
+    const getBlock = name => activity.registeredBlocks[name];
+
+    test("registers blocks", () => {
+        expect(activity.registeredBlocks).toHaveProperty("yourblock");
+    });
+
+    test("block flow works", () => {
+        const block = getBlock("yourblock");
+        // Replace with actual args for your block
+        const result = block.flow([1 / 4, "sol"], logo, 0, 5);
+        expect(result).toEqual(["sol", 1]);
+    });
+});
+```
+
+### Common Mocks
+
+| Global                         | Purpose                            |
+| ------------------------------ | ---------------------------------- |
+| `activity.errorMsg`            | Captures error messages            |
+| `activity.blocks.blockList`    | Simulates block connections        |
+| `logo.parseArg`                | Returns values for block arguments |
+| `activity.turtles.ithTurtle()` | Returns turtle state               |
+
+### Tips
+
+1. Check the source file's `flow()` or `arg()` method to understand what it expects
+2. Mock only what's needed for the specific test
+3. Use `jest.fn()` for methods you want to verify were called
+4. Run `npx prettier --write` on your test file before committing

js/README.md

@@ -4,6 +4,10 @@ MusicBlocks/js
 The core code for Music Blocks resides in this directory, the blocks and the turtleactions
 subdirectory.
 
+## Testing
+
+For writing unit tests for block files, see [docs/TESTING.md](../docs/TESTING.md).
+
 * `activity.js` -- where the menus are defined
 
 Logo code