Add comprehensive test suite and CI workflow

- Add test fixtures for various markdown scenarios
- Implement bash test script with 25 test cases
- Add GitHub Actions workflow for Linux testing
- Use official pandoc/actions/setup for installation
- Test with latest pandoc version
- Include shellcheck linting
- Test with pre-commit for idempotency
- Add CI badge to README

Co-authored-by: Amp <[email protected]>
Amp-Thread-ID: https://ampcode.com/threads/T-a4b3b491-de29-4cf7-a459-f324a9c0c53b

Author: jupblb

.github/workflows/test.yml

@@ -0,0 +1,51 @@
+name: Test
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v5
+
+    - name: Install pandoc
+      uses: pandoc/actions/setup@v1
+
+    - name: Show pandoc version
+      run: pandoc --version
+
+    - name: Run tests
+      run: ./tests/test_pandoc_format.sh
+
+    - name: Test with pre-commit
+      run: |
+        pip install pre-commit
+        pre-commit run --all-files || true
+        # Run again to ensure idempotency
+        pre-commit run --all-files
+
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v5
+
+    - name: Shellcheck
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y shellcheck
+        shellcheck pandoc-format
+        shellcheck tests/test_pandoc_format.sh
+
+    - name: Check file permissions
+      run: |
+        test -x pandoc-format || (echo "pandoc-format is not executable" && exit 1)
+        test -x tests/test_pandoc_format.sh || (echo "test script is not executable" && exit 1)

README.md

@@ -1,5 +1,7 @@
 # pre-commit-pandoc
 
+[![Test](https://github.com/jupblb/pre-commit-pandoc/actions/workflows/test.yml/badge.svg)](https://github.com/jupblb/pre-commit-pandoc/actions/workflows/test.yml)
+
 A [pre-commit] hook for formatting Markdown files using [pandoc].
 
 ## Features

tests/fixtures/already-formatted.md

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+# Already Formatted Document
+
+This document is already properly formatted with 80-column width and reference
+links.
+
+## Section with Links
+
+This paragraph contains [a properly formatted link] that already uses reference
+style formatting.
+
+## Lists
+
+- First item
+- Second item
+- Third item
+
+## Code Block
+
+``` bash
+echo "This is already formatted"
+```
+
+  [a properly formatted link]: https://example.com

tests/fixtures/complex.md

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+# Complex Markdown Document
+
+This document contains various markdown elements to test comprehensive formatting.
+
+## Code Blocks
+
+```python
+def hello_world():
+    print("Hello, World!")
+    return True
+```
+
+## Tables
+
+| Column 1 | Column 2 | Column 3 |
+|----------|----------|----------|
+| Data 1   | Data 2   | Data 3   |
+| More data that is quite long | Even more data | Last column |
+
+## Links and References
+
+Here's [a link to GitHub](https://github.com) and [another link to Google](https://google.com).
+
+We also have [repeated link to GitHub](https://github.com) that should use the same reference.
+
+## Blockquotes
+
+> This is a blockquote with some text that should be wrapped appropriately
+> when the line length exceeds the configured column width.
+
+## Nested Lists
+
+1. First ordered item
+   - Nested unordered item
+   - Another nested item with [a link](https://example.org)
+2. Second ordered item
+   1. Nested ordered item
+   2. Another nested ordered
+
+## Inline Code and Emphasis
+
+This paragraph contains `inline code`, *italic text*, **bold text**, and ***bold italic text***.
+
+## Horizontal Rule
+
+---
+
+## Images
+
+![Alt text for image](https://example.com/image.png "Image title")

tests/fixtures/simple.md

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+# Simple Test Document
+
+This is a simple test with [inline link](https://example.com) that should be converted to reference style by default.
+
+A paragraph with very long lines that exceed the default 80 character column width limit and should be wrapped appropriately when formatted by pandoc.
+
+## Lists
+
+- First item
+- Second item with [a link](https://github.com)
+- Third item