core: add helpers for working with paths across OSes (#1102)

packages/core/README.md

@@ -309,4 +309,27 @@ outputs:
 runs:
   using: 'node12'
   main: 'dist/index.js'
-```
+```
+
+#### Filesystem path helpers
+
+You can use these methods to manipulate file paths across operating systems.
+
+The `toPosixPath` function converts input paths to Posix-style (Linux) paths.
+The `toWin32Path` function converts input paths to Windows-style paths. These
+functions work independently of the underlying runner operating system.
+
+```js
+toPosixPath('\\foo\\bar') // => /foo/bar
+toWin32Path('/foo/bar') // => \foo\bar
+```
+
+The `toPlatformPath` function converts input paths to the expected value on the runner's operating system.
+
+```js
+// On a Windows runner.
+toPlatformPath('/foo/bar') // => \foo\bar
+
+// On a Linux runner.
+toPlatformPath('\\foo\\bar') // => /foo/bar
+```

packages/core/__tests__/path-utils.test.ts

@@ -0,0 +1,162 @@
+import * as path from 'path'
+
+import {toPlatformPath, toPosixPath, toWin32Path} from '../src/path-utils'
+
+describe('#toPosixPath', () => {
+  const cases: {
+    only?: boolean
+    name: string
+    input: string
+    expected: string
+  }[] = [
+    {
+      name: 'empty string',
+      input: '',
+      expected: ''
+    },
+    {
+      name: 'single value',
+      input: 'foo',
+      expected: 'foo'
+    },
+    {
+      name: 'with posix relative',
+      input: 'foo/bar/baz',
+      expected: 'foo/bar/baz'
+    },
+    {
+      name: 'with posix absolute',
+      input: '/foo/bar/baz',
+      expected: '/foo/bar/baz'
+    },
+    {
+      name: 'with win32 relative',
+      input: 'foo\\bar\\baz',
+      expected: 'foo/bar/baz'
+    },
+    {
+      name: 'with win32 absolute',
+      input: '\\foo\\bar\\baz',
+      expected: '/foo/bar/baz'
+    },
+    {
+      name: 'with a mix',
+      input: '\\foo/bar/baz',
+      expected: '/foo/bar/baz'
+    }
+  ]
+
+  for (const tc of cases) {
+    const fn = tc.only ? it.only : it
+    fn(tc.name, () => {
+      const result = toPosixPath(tc.input)
+      expect(result).toEqual(tc.expected)
+    })
+  }
+})
+
+describe('#toWin32Path', () => {
+  const cases: {
+    only?: boolean
+    name: string
+    input: string
+    expected: string
+  }[] = [
+    {
+      name: 'empty string',
+      input: '',
+      expected: ''
+    },
+    {
+      name: 'single value',
+      input: 'foo',
+      expected: 'foo'
+    },
+    {
+      name: 'with posix relative',
+      input: 'foo/bar/baz',
+      expected: 'foo\\bar\\baz'
+    },
+    {
+      name: 'with posix absolute',
+      input: '/foo/bar/baz',
+      expected: '\\foo\\bar\\baz'
+    },
+    {
+      name: 'with win32 relative',
+      input: 'foo\\bar\\baz',
+      expected: 'foo\\bar\\baz'
+    },
+    {
+      name: 'with win32 absolute',
+      input: '\\foo\\bar\\baz',
+      expected: '\\foo\\bar\\baz'
+    },
+    {
+      name: 'with a mix',
+      input: '\\foo/bar\\baz',
+      expected: '\\foo\\bar\\baz'
+    }
+  ]
+
+  for (const tc of cases) {
+    const fn = tc.only ? it.only : it
+    fn(tc.name, () => {
+      const result = toWin32Path(tc.input)
+      expect(result).toEqual(tc.expected)
+    })
+  }
+})
+
+describe('#toPlatformPath', () => {
+  const cases: {
+    only?: boolean
+    name: string
+    input: string
+    expected: string
+  }[] = [
+    {
+      name: 'empty string',
+      input: '',
+      expected: ''
+    },
+    {
+      name: 'single value',
+      input: 'foo',
+      expected: 'foo'
+    },
+    {
+      name: 'with posix relative',
+      input: 'foo/bar/baz',
+      expected: path.join('foo', 'bar', 'baz')
+    },
+    {
+      name: 'with posix absolute',
+      input: '/foo/bar/baz',
+      expected: path.join(path.sep, 'foo', 'bar', 'baz')
+    },
+    {
+      name: 'with win32 relative',
+      input: 'foo\\bar\\baz',
+      expected: path.join('foo', 'bar', 'baz')
+    },
+    {
+      name: 'with win32 absolute',
+      input: '\\foo\\bar\\baz',
+      expected: path.join(path.sep, 'foo', 'bar', 'baz')
+    },
+    {
+      name: 'with a mix',
+      input: '\\foo/bar\\baz',
+      expected: path.join(path.sep, 'foo', 'bar', 'baz')
+    }
+  ]
+
+  for (const tc of cases) {
+    const fn = tc.only ? it.only : it
+    fn(tc.name, () => {
+      const result = toPlatformPath(tc.input)
+      expect(result).toEqual(tc.expected)
+    })
+  }
+})

packages/core/src/core.ts

@@ -369,3 +369,8 @@ export {summary} from './summary'
  * @deprecated use core.summary
  */
 export {markdownSummary} from './summary'
+
+/**
+ * Path exports
+ */
+export {toPosixPath, toWin32Path, toPlatformPath} from './path-utils'

packages/core/src/path-utils.ts

@@ -0,0 +1,35 @@
+import * as path from 'path'
+
+/**
+ * toPosixPath converts the given path to the posix form. On Windows, \\ will be
+ * replaced with /.
+ *
+ * @param pth. Path to transform.
+ * @return string Posix path.
+ */
+export function toPosixPath(pth: string): string {
+  return pth.replace(/[\\]/g, '/')
+}
+
+/**
+ * toWin32Path converts the given path to the win32 form. On Linux, / will be
+ * replaced with \\.
+ *
+ * @param pth. Path to transform.
+ * @return string Win32 path.
+ */
+export function toWin32Path(pth: string): string {
+  return pth.replace(/[/]/g, '\\')
+}
+
+/**
+ * toPlatformPath converts the given path to a platform-specific path. It does
+ * this by replacing instances of / and \ with the platform-specific path
+ * separator.
+ *
+ * @param pth The path to platformize.
+ * @return string The platform-specific path.
+ */
+export function toPlatformPath(pth: string): string {
+  return pth.replace(/[/\\]/g, path.sep)
+}