From 2fac626e466d724629946747c4514dac906864b2 Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Fri, 26 Dec 2025 20:38:17 -0800
Subject: [PATCH] temp tests

---
 package.json              |   3 +-
 src/index.tsx             |  49 ++-
 src/tests/index.test.tsx  | 748 ++++++++++++++++++++++++++++++++++++++
 src/tests/test_helpers.ts |  32 ++
 4 files changed, 822 insertions(+), 10 deletions(-)
 create mode 100644 src/tests/index.test.tsx
 create mode 100644 src/tests/test_helpers.ts

diff --git a/package.json b/package.json
index a1aa4c9..78e595e 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,8 @@
   "module": "src/index.ts",
   "type": "module",
   "scripts": {
-    "dev": "bun run --hot server.tsx"
+    "dev": "bun run --hot server.tsx",
+    "test": "bun test"
   },
   "devDependencies": {
     "@types/bun": "latest"
diff --git a/src/index.tsx b/src/index.tsx
index 863d34c..107ec27 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -1,18 +1,19 @@
 import type { JSX } from 'hono/jsx'
 import { type TagDef, UnitlessProps } from './types'
 
-const styles: Record<string, Record<string, string>> = {}
+export const styles: Record<string, Record<string, string>> = {}
 export const Styles = () => <style dangerouslySetInnerHTML={{ __html: stylesToCSS(styles) }} />
 
 // turns style object into string CSS definition
-function stylesToCSS(styles: Record<string, Record<string, string>>): string {
+export function stylesToCSS(styles: Record<string, Record<string, string>>): string {
   let out: string[] = []
 
   for (const [selector, style] of Object.entries(styles)) {
+    if (Object.keys(style).length === 0) continue
+
     out.push(`.${selector} {`)
-    for (const [name, value] of Object.entries(style)) {
+    for (const [name, value] of Object.entries(style).sort(([a], [b]) => a.localeCompare(b)))
       out.push(`  ${name}: ${value};`)
-    }
     out.push(`}\n`)
   }
 
@@ -73,7 +74,7 @@ function makeComponent(baseName: string, rootDef: TagDef, rootProps: Record<stri
     }
     if (!variantDef) continue
 
-    classNames.push(`${variantName}-${variantKey}`)
+    classNames.push(variantKey === true ? variantName : `${variantName}-${variantKey}`)
   }
 
   return ({ children, ...props }: { children: any, [key: string]: any }) =>
@@ -85,19 +86,49 @@ function registerStyles(name: string, def: TagDef) {
   const rootClassName = makeClassName(name)
   styles[rootClassName] ??= makeStyle(def)
 
+  for (const [state, style] of Object.entries(def.states ?? {}))
+    styles[`${rootClassName}${state}`] = makeStyle(style)
+
   for (const [partName, partDef] of Object.entries(def.parts ?? {})) {
     const partClassName = makeClassName(name, partName)
     styles[partClassName] ??= makeStyle(partDef)
+    for (const [state, style] of Object.entries(partDef.states ?? {}))
+      styles[`${partClassName}${state}`] = makeStyle(style)
+
   }
 
   for (const [variantName, variantConfig] of Object.entries(def.variants ?? {})) {
-    for (const [variantKey, variantDef] of Object.entries(variantConfig as Record<string, TagDef>)) {
-      const className = makeClassName(name, undefined, variantName, variantKey)
+    // Check if it's a boolean variant (has layout/look/parts directly) or a keyed variant
+    if ('parts' in variantConfig || 'layout' in variantConfig || 'look' in variantConfig) {
+      // Boolean variant - treat variantConfig as TagDef
+      const variantDef = variantConfig as TagDef
+      const baseClassName = makeClassName(name)
+      const className = `${baseClassName}.${variantName}`
       styles[className] ??= makeStyle({ layout: variantDef.layout, look: variantDef.look })
+      for (const [state, style] of Object.entries(variantDef.states ?? {}))
+        styles[`${className}${state}`] = makeStyle(style)
 
       for (const [partName, partDef] of Object.entries(variantDef.parts ?? {})) {
-        const partClassName = makeClassName(name, partName, variantName, variantKey)
+        const basePartClassName = makeClassName(name, partName)
+        const partClassName = `${basePartClassName}.${variantName}`
         styles[partClassName] ??= makeStyle(partDef)
+        for (const [state, style] of Object.entries(partDef.states ?? {}))
+          styles[`${partClassName}${state}`] = makeStyle(style)
+      }
+    } else {
+      // Keyed variant - iterate over the keys
+      for (const [variantKey, variantDef] of Object.entries(variantConfig as Record<string, TagDef>)) {
+        const className = makeClassName(name, undefined, variantName, variantKey)
+        styles[className] ??= makeStyle({ layout: variantDef.layout, look: variantDef.look })
+        for (const [state, style] of Object.entries(variantDef.states ?? {}))
+          styles[`${className}${state}`] = makeStyle(style)
+
+        for (const [partName, partDef] of Object.entries(variantDef.parts ?? {})) {
+          const partClassName = makeClassName(name, partName, variantName, variantKey)
+          styles[partClassName] ??= makeStyle(partDef)
+          for (const [state, style] of Object.entries(partDef.states ?? {}))
+            styles[`${partClassName}${state}`] = makeStyle(style)
+        }
       }
     }
   }
@@ -119,7 +150,7 @@ export function define(nameOrDef: string | TagDef, defIfNamed?: TagDef) {
       parts[part] = makeComponent(name, def, props, part)
 
     parts.Root = makeComponent(name, def, props)
-    return def.render ? def.render({ props, parts }) : <parts.Root {...props}>{props.children}</parts.Root>
+    return def.render?.({ props, parts }) ?? <parts.Root {...props}>{props.children}</parts.Root>
   }
 }
 
diff --git a/src/tests/index.test.tsx b/src/tests/index.test.tsx
new file mode 100644
index 0000000..19424b0
--- /dev/null
+++ b/src/tests/index.test.tsx
@@ -0,0 +1,748 @@
+import { describe, test, expect } from 'bun:test'
+import { define } from '../index'
+import { renderToString, getStylesCSS, parseCSS } from './test_helpers'
+
+describe('define - basic functionality', () => {
+  test('creates a component function', () => {
+    const Component = define({
+      layout: { display: 'flex' }
+    })
+
+    expect(typeof Component).toBe('function')
+  })
+
+  test('component returns a JSX element', () => {
+    const Component = define({
+      layout: { display: 'flex' }
+    })
+
+    const result = Component({})
+    expect(result).toBeDefined()
+    expect(typeof result).toBe('object')
+  })
+
+  test('applies className to rendered element', () => {
+    const Component = define('MyComponent', {
+      layout: { display: 'flex' }
+    })
+
+    const html = renderToString(Component({}))
+    expect(html).toContain('class="MyComponent"')
+  })
+
+  test('generates unique anonymous component names', () => {
+    const Component1 = define({ layout: { display: 'flex' } })
+    const Component2 = define({ layout: { display: 'block' } })
+
+    const html1 = renderToString(Component1({}))
+    const html2 = renderToString(Component2({}))
+
+    // Should have different auto-generated names
+    expect(html1).toMatch(/class="Def\d+"/)
+    expect(html2).toMatch(/class="Def\d+"/)
+    expect(html1).not.toBe(html2)
+  })
+
+  test('renders default div element', () => {
+    const Component = define('DivTest', {
+      layout: { display: 'flex' }
+    })
+
+    const html = renderToString(Component({}))
+    expect(html).toContain('<div')
+    expect(html).toContain('</div>')
+  })
+
+  test('respects custom base element', () => {
+    const Component = define('ButtonTest', {
+      base: 'button',
+      look: { color: 'blue' }
+    })
+
+    const html = renderToString(Component({}))
+    expect(html).toContain('<button')
+    expect(html).toContain('</button>')
+  })
+
+  test('passes children through to component', () => {
+    const Component = define({})
+
+    const html = renderToString(Component({ children: 'Hello World' }))
+    expect(html).toContain('Hello World')
+  })
+
+  test('passes additional props through to component', () => {
+    const Component = define({})
+
+    const html = renderToString(Component({ id: 'test-id', 'data-test': 'value' }))
+    expect(html).toContain('id="test-id"')
+    expect(html).toContain('data-test="value"')
+  })
+})
+
+describe('CSS generation - camelCase to kebab-case', () => {
+  test('converts camelCase properties to kebab-case', () => {
+    define('CamelTest', {
+      layout: {
+        flexDirection: 'column',
+        alignItems: 'center',
+        justifyContent: 'space-between'
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('flex-direction: column')
+    expect(css).toContain('align-items: center')
+    expect(css).toContain('justify-content: space-between')
+  })
+
+  test('handles consecutive capital letters', () => {
+    define('ConsecutiveTest', {
+      look: {
+        backgroundColor: 'red',
+        borderRadius: 5
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('background-color: red')
+    expect(css).toContain('border-radius: 5px')
+  })
+})
+
+describe('CSS generation - numeric values and units', () => {
+  test('adds px unit to numeric layout values', () => {
+    define('NumericTest', {
+      layout: {
+        width: 100,
+        height: 200,
+        padding: 16,
+        margin: 8
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['NumericTest']?.['width']).toBe('100px')
+    expect(styles['NumericTest']?.['height']).toBe('200px')
+    expect(styles['NumericTest']?.['padding']).toBe('16px')
+    expect(styles['NumericTest']?.['margin']).toBe('8px')
+  })
+
+  test('preserves string values without adding px', () => {
+    define('StringTest', {
+      layout: {
+        width: '100%',
+        height: 'auto',
+        margin: '0 auto',
+        padding: '1rem'
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['StringTest']?.['width']).toBe('100%')
+    expect(styles['StringTest']?.['height']).toBe('auto')
+    expect(styles['StringTest']?.['margin']).toBe('0 auto')
+    expect(styles['StringTest']?.['padding']).toBe('1rem')
+  })
+
+  test('does not add px to unitless properties', () => {
+    define('UnitlessTest', {
+      layout: {
+        flex: 1,
+        flexGrow: 2,
+        flexShrink: 1,
+        zIndex: 10,
+        order: 3
+      },
+      look: {
+        opacity: 0.5,
+        fontWeight: 700,
+        lineHeight: 1.5
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['UnitlessTest']?.['flex']).toBe('1')
+    expect(styles['UnitlessTest']?.['flex-grow']).toBe('2')
+    expect(styles['UnitlessTest']?.['flex-shrink']).toBe('1')
+    expect(styles['UnitlessTest']?.['z-index']).toBe('10')
+    expect(styles['UnitlessTest']?.['order']).toBe('3')
+    expect(styles['UnitlessTest']?.['opacity']).toBe('0.5')
+    expect(styles['UnitlessTest']?.['font-weight']).toBe('700')
+    expect(styles['UnitlessTest']?.['line-height']).toBe('1.5')
+  })
+
+  test('handles numeric zero values correctly', () => {
+    define('ZeroTest', {
+      layout: {
+        margin: 0,
+        padding: 0,
+        zIndex: 0
+      },
+      look: {
+        opacity: 0
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['ZeroTest']?.['margin']).toBe('0px')
+    expect(styles['ZeroTest']?.['padding']).toBe('0px')
+    expect(styles['ZeroTest']?.['z-index']).toBe('0')
+    expect(styles['ZeroTest']?.['opacity']).toBe('0')
+  })
+})
+
+describe('CSS generation - layout and look', () => {
+  test('generates CSS for layout properties', () => {
+    define('LayoutTest', {
+      layout: {
+        display: 'flex',
+        flexDirection: 'column',
+        gap: 16,
+        padding: 20
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.LayoutTest')
+    expect(css).toContain('display: flex')
+    expect(css).toContain('flex-direction: column')
+    expect(css).toContain('gap: 16px')
+    expect(css).toContain('padding: 20px')
+  })
+
+  test('generates CSS for look properties', () => {
+    define('LookTest', {
+      look: {
+        color: 'blue',
+        backgroundColor: 'white',
+        fontSize: 16,
+        fontWeight: 600
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.LookTest')
+    expect(css).toContain('color: blue')
+    expect(css).toContain('background-color: white')
+    expect(css).toContain('font-size: 16px')
+    expect(css).toContain('font-weight: 600')
+  })
+
+  test('combines layout and look properties', () => {
+    define('CombinedTest', {
+      layout: {
+        display: 'flex',
+        padding: 16
+      },
+      look: {
+        color: 'blue',
+        backgroundColor: 'white'
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    const combined = styles['CombinedTest']!
+    expect(combined['display']).toBe('flex')
+    expect(combined['padding']).toBe('16px')
+    expect(combined['color']).toBe('blue')
+    expect(combined['background-color']).toBe('white')
+  })
+})
+
+describe('CSS generation - parts', () => {
+  test('generates separate CSS for each part', () => {
+    define('PartTest', {
+      layout: { display: 'flex' },
+      parts: {
+        Header: { base: 'header', look: { color: 'red', fontSize: 20 } },
+        Body: { base: 'main', layout: { padding: 20 } },
+        Footer: { base: 'footer', look: { fontSize: 12 } }
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['PartTest_Header']?.['color']).toBe('red')
+    expect(styles['PartTest_Header']?.['font-size']).toBe('20px')
+    expect(styles['PartTest_Body']?.['padding']).toBe('20px')
+    expect(styles['PartTest_Footer']?.['font-size']).toBe('12px')
+  })
+
+  test('part className format is ComponentName_PartName', () => {
+    define('ComponentWithParts', {
+      parts: {
+        MyPart: { look: { color: 'green' } }
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.ComponentWithParts_MyPart')
+  })
+})
+
+describe('components with parts', () => {
+  test('creates part components accessible through render function', () => {
+    let capturedParts: any
+
+    const Component = define('PartRenderTest', {
+      parts: {
+        Header: { base: 'header' },
+        Body: { base: 'main' }
+      },
+      render: ({ props, parts }) => {
+        capturedParts = parts
+        return <parts.Root {...props}>{props.children}</parts.Root>
+      }
+    })
+
+    Component({})
+
+    expect(typeof capturedParts.Header).toBe('function')
+    expect(typeof capturedParts.Body).toBe('function')
+    expect(typeof capturedParts.Root).toBe('function')
+  })
+
+  test('part components render with correct className', () => {
+    const Component = define('PartClassTest', {
+      parts: {
+        Header: { base: 'header' }
+      },
+      render: ({ props, parts }) => {
+        return <parts.Header>Header Content</parts.Header>
+      }
+    })
+
+    const html = renderToString(Component({}))
+    expect(html).toContain('class="PartClassTest_Header"')
+    expect(html).toContain('<header')
+  })
+
+  test('parts render with correct base elements', () => {
+    const Component = define('PartBaseTest', {
+      parts: {
+        Header: { base: 'header' },
+        Main: { base: 'main' },
+        Footer: { base: 'footer' }
+      },
+      render: ({ props, parts }) => {
+        return (
+          <div>
+            <parts.Header>Header</parts.Header>
+            <parts.Main>Main</parts.Main>
+            <parts.Footer>Footer</parts.Footer>
+          </div>
+        )
+      }
+    })
+
+    const html = renderToString(Component({}))
+    expect(html).toContain('<header')
+    expect(html).toContain('<main')
+    expect(html).toContain('<footer')
+  })
+})
+
+describe('variants - boolean variants', () => {
+  test('applies boolean variant class when true', () => {
+    const Component = define('BoolVariant', {
+      layout: { display: 'flex' },
+      variants: {
+        primary: {
+          look: { color: 'blue' }
+        }
+      }
+    })
+
+    const html = renderToString(Component({ primary: true }))
+    // Boolean variants add just the variant name as a class
+    expect(html).toContain('class="BoolVariant primary"')
+  })
+
+  test('does not apply boolean variant class when false or absent', () => {
+    const Component = define('BoolVariantFalse', {
+      variants: {
+        active: {
+          look: { backgroundColor: 'green' }
+        }
+      }
+    })
+
+    const htmlFalse = renderToString(Component({ active: false }))
+    const htmlAbsent = renderToString(Component({}))
+
+    // When false or absent, variant class should not be added (check the class attribute)
+    expect(htmlFalse).toContain('class="BoolVariantFalse"')
+    expect(htmlFalse).not.toContain('class="BoolVariantFalse active')
+    expect(htmlAbsent).toContain('class="BoolVariantFalse"')
+    expect(htmlAbsent).not.toContain(' active')
+  })
+
+  test('generates CSS for component with boolean variant', () => {
+    define('BoolVariantCSS', {
+      layout: { display: 'block' },
+      variants: {
+        active: {
+          look: { backgroundColor: 'green' }
+        }
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.BoolVariantCSS')
+    expect(css).toContain('display: block')
+  })
+})
+
+describe('variants - string/enum variants', () => {
+  test('applies string variant class', () => {
+    const Component = define('StringVariant', {
+      variants: {
+        size: {
+          small: { layout: { padding: 8 } },
+          medium: { layout: { padding: 16 } },
+          large: { layout: { padding: 24 } }
+        }
+      }
+    })
+
+    const htmlSmall = renderToString(Component({ size: 'small' }))
+    const htmlLarge = renderToString(Component({ size: 'large' }))
+
+    expect(htmlSmall).toContain('class="StringVariant size-small"')
+    expect(htmlLarge).toContain('class="StringVariant size-large"')
+  })
+
+  test('generates CSS for each variant option', () => {
+    define('ColorVariant', {
+      variants: {
+        color: {
+          red: { look: { color: 'red', backgroundColor: '#ffeeee' } },
+          blue: { look: { color: 'blue', backgroundColor: '#eeeeff' } },
+          green: { look: { color: 'green', backgroundColor: '#eeffee' } }
+        }
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['ColorVariant.color-red']?.['color']).toBe('red')
+    expect(styles['ColorVariant.color-blue']?.['color']).toBe('blue')
+    expect(styles['ColorVariant.color-green']?.['color']).toBe('green')
+  })
+
+  test('applies multiple variant classes', () => {
+    const Component = define('MultiVariant', {
+      variants: {
+        size: {
+          small: { layout: { padding: 8 } },
+          large: { layout: { padding: 24 } }
+        },
+        color: {
+          red: { look: { color: 'red' } },
+          blue: { look: { color: 'blue' } }
+        }
+      }
+    })
+
+    const html = renderToString(Component({ size: 'small', color: 'blue' }))
+    expect(html).toContain('size-small')
+    expect(html).toContain('color-blue')
+  })
+
+  test('ignores undefined variant values', () => {
+    const Component = define('UndefinedVariant', {
+      variants: {
+        size: {
+          small: { layout: { padding: 8 } }
+        }
+      }
+    })
+
+    const html = renderToString(Component({ size: 'nonexistent' }))
+    expect(html).toContain('class="UndefinedVariant"')
+    expect(html).not.toContain('size-nonexistent')
+  })
+
+  test('ignores non-variant props', () => {
+    const Component = define('NonVariantProps', {
+      variants: {
+        size: {
+          small: { layout: { padding: 8 } }
+        }
+      }
+    })
+
+    const html = renderToString(Component({ size: 'small', randomProp: 'value', id: 'test' }))
+    expect(html).toContain('size-small')
+    expect(html).toContain('id="test"')
+    expect(html).toContain('randomProp="value"')
+  })
+})
+
+describe('variants with parts', () => {
+  test('generates CSS for variant parts', () => {
+    define('VariantParts', {
+      parts: {
+        Header: { base: 'header' }
+      },
+      variants: {
+        theme: {
+          dark: {
+            parts: {
+              Header: { look: { color: 'white', backgroundColor: 'black' } }
+            }
+          },
+          light: {
+            parts: {
+              Header: { look: { color: 'black', backgroundColor: 'white' } }
+            }
+          }
+        }
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['VariantParts_Header.theme-dark']?.['color']).toBe('white')
+    expect(styles['VariantParts_Header.theme-dark']?.['background-color']).toBe('black')
+    expect(styles['VariantParts_Header.theme-light']?.['color']).toBe('black')
+    expect(styles['VariantParts_Header.theme-light']?.['background-color']).toBe('white')
+  })
+
+  test('part elements include variant classes', () => {
+    const Component = define('VariantPartClass', {
+      parts: {
+        Header: { base: 'header' }
+      },
+      variants: {
+        size: {
+          large: { layout: { padding: 20 } }
+        }
+      },
+      render: ({ props, parts }) => {
+        return <parts.Header>Header Content</parts.Header>
+      }
+    })
+
+    const html = renderToString(Component({ size: 'large' }))
+    expect(html).toContain('VariantPartClass_Header')
+    expect(html).toContain('size-large')
+  })
+})
+
+describe('custom render function', () => {
+  test('uses custom render when provided', () => {
+    const Component = define('CustomRender', {
+      layout: { display: 'flex' },
+      render: ({ props, parts }) => {
+        return <div class="custom-wrapper">{props.children}</div>
+      }
+    })
+
+    const html = renderToString(Component({ children: 'Content' }))
+    expect(html).toContain('class="custom-wrapper"')
+    expect(html).toContain('Content')
+  })
+
+  test('custom render receives props', () => {
+    let receivedProps: any
+
+    const Component = define({
+      render: ({ props, parts }) => {
+        receivedProps = props
+        return <parts.Root {...props}>{props.children}</parts.Root>
+      }
+    })
+
+    Component({ testProp: 'value', children: 'Test' })
+
+    expect(receivedProps.testProp).toBe('value')
+    expect(receivedProps.children).toBe('Test')
+  })
+
+  test('custom render can compose parts', () => {
+    const Component = define('ComposeParts', {
+      parts: {
+        Header: { base: 'header' },
+        Body: { base: 'main' },
+        Footer: { base: 'footer' }
+      },
+      render: ({ props, parts }) => {
+        return (
+          <parts.Root>
+            <parts.Header>Header</parts.Header>
+            <parts.Body>{props.children}</parts.Body>
+            <parts.Footer>Footer</parts.Footer>
+          </parts.Root>
+        )
+      }
+    })
+
+    const html = renderToString(Component({ children: 'Main Content' }))
+    expect(html).toContain('<header')
+    expect(html).toContain('<main')
+    expect(html).toContain('<footer')
+    expect(html).toContain('Main Content')
+  })
+})
+
+describe('Styles component', () => {
+  test('Styles is accessible via define.Styles', () => {
+    expect(typeof define.Styles).toBe('function')
+  })
+
+  test('Styles returns a style element', () => {
+    const result = define.Styles() as any
+    expect(result).toBeDefined()
+    expect(result.props.dangerouslySetInnerHTML).toBeDefined()
+  })
+
+  test('Styles renders to HTML with CSS', () => {
+    define('StylesComp1', { layout: { width: 100 } })
+
+    const html = renderToString(define.Styles())
+    expect(html).toContain('<style>')
+    expect(html).toContain('.StylesComp1')
+    expect(html).toContain('width: 100px')
+    expect(html).toContain('</style>')
+  })
+
+  test('Styles includes CSS for all registered components', () => {
+    define('StylesComp2', { layout: { width: 100 } })
+    define('StylesComp3', { layout: { height: 200 } })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.StylesComp2')
+    expect(css).toContain('width: 100px')
+    expect(css).toContain('.StylesComp3')
+    expect(css).toContain('height: 200px')
+  })
+
+  test('Styles includes variant CSS', () => {
+    define('StylesVariant', {
+      variants: {
+        size: {
+          small: { layout: { padding: 8 } },
+          large: { layout: { padding: 24 } }
+        }
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.StylesVariant.size-small')
+    expect(css).toContain('padding: 8px')
+    expect(css).toContain('.StylesVariant.size-large')
+    expect(css).toContain('padding: 24px')
+  })
+
+  test('Styles includes part CSS', () => {
+    define('StylesPart', {
+      parts: {
+        Header: { look: { color: 'red' } },
+        Body: { look: { color: 'blue' } }
+      }
+    })
+
+    const css = getStylesCSS()
+    expect(css).toContain('.StylesPart_Header')
+    expect(css).toContain('color: red')
+    expect(css).toContain('.StylesPart_Body')
+    expect(css).toContain('color: blue')
+  })
+})
+
+describe('edge cases', () => {
+  test('handles empty definition', () => {
+    const Component = define({})
+    const html = renderToString(Component({}))
+
+    expect(html).toBeDefined()
+    expect(html).toMatch(/class="Def\d+"/)
+  })
+
+  test('handles definition with only parts', () => {
+    const Component = define({
+      parts: {
+        Header: { base: 'header' }
+      }
+    })
+
+    const result = Component({})
+    expect(result).toBeDefined()
+  })
+
+  test('handles definition with only variants', () => {
+    const Component = define({
+      variants: {
+        size: {
+          small: { layout: { padding: 8 } }
+        }
+      }
+    })
+
+    const html = renderToString(Component({ size: 'small' }))
+    expect(html).toContain('size-small')
+  })
+
+  test('does not duplicate styles when registered multiple times', () => {
+    define('NoDuplicate', { layout: { width: 100 } })
+    define('NoDuplicate', { layout: { width: 200 } })
+
+    const styles = parseCSS(getStylesCSS())
+    // Should keep first value (??= operator)
+    expect(styles['NoDuplicate']?.['width']).toBe('100px')
+  })
+
+  test('handles complex nested structures', () => {
+    define('ComplexNested', {
+      layout: { display: 'grid' },
+      parts: {
+        Container: { layout: { padding: 16 } },
+        Item: { look: { fontSize: 14 } }
+      },
+      variants: {
+        theme: {
+          dark: {
+            look: { backgroundColor: 'black' },
+            parts: {
+              Container: { look: { backgroundColor: '#222' } },
+              Item: { look: { color: 'white' } }
+            }
+          }
+        }
+      }
+    })
+
+    const styles = parseCSS(getStylesCSS())
+    expect(styles['ComplexNested']?.['display']).toBe('grid')
+    expect(styles['ComplexNested_Container']?.['padding']).toBe('16px')
+    expect(styles['ComplexNested_Item']?.['font-size']).toBe('14px')
+    expect(styles['ComplexNested.theme-dark']?.['background-color']).toBe('black')
+    expect(styles['ComplexNested_Container.theme-dark']?.['background-color']).toBe('#222')
+    expect(styles['ComplexNested_Item.theme-dark']?.['color']).toBe('white')
+  })
+
+  test('handles JSX children correctly', () => {
+    const Component = define('ChildrenTest', {})
+
+    const html = renderToString(Component({
+      children: <span>Nested Element</span>
+    }))
+    expect(html).toContain('<span>Nested Element</span>')
+  })
+
+  test('handles multiple children', () => {
+    const Component = define('MultiChildren', {
+      render: ({ props, parts }) => {
+        return <parts.Root>{props.children}</parts.Root>
+      }
+    })
+
+    const html = renderToString(Component({
+      children: [
+        <div>First</div>,
+        <div>Second</div>
+      ]
+    }))
+    expect(html).toContain('First')
+    expect(html).toContain('Second')
+  })
+})
diff --git a/src/tests/test_helpers.ts b/src/tests/test_helpers.ts
new file mode 100644
index 0000000..d615394
--- /dev/null
+++ b/src/tests/test_helpers.ts
@@ -0,0 +1,32 @@
+import { define } from '../index'
+
+export function renderToString(jsx: any): string {
+  return jsx.toString()
+}
+
+export function getStylesCSS(): string {
+  const StylesComponent = define.Styles
+  const result = StylesComponent() as any
+  return result.props.dangerouslySetInnerHTML.__html as string
+}
+
+export function parseCSS(css: string): Record<string, Record<string, string>> {
+  const styles: Record<string, Record<string, string>> = {}
+  const classMatches = Array.from(css.matchAll(/\.([^\s{]+)\s*\{([^}]+)\}/g))
+
+  for (const match of classMatches) {
+    if (!match[1] || !match[2]) continue
+
+    const className = match[1]
+    const cssText = match[2]
+    styles[className] = {}
+
+    const propMatches = Array.from(cssText.matchAll(/\s*([^:]+):\s*([^;]+);/g))
+    for (const propMatch of propMatches) {
+      if (!propMatch[1] || !propMatch[2]) continue
+      styles[className]![propMatch[1].trim()] = propMatch[2].trim()
+    }
+  }
+
+  return styles
+}