Fix stripIndents and add regression tests (#129)

src/stripIndent/fixtures/maintainEmptyLines.txt

@@ -0,0 +1,3 @@
+wow such indent gone
+
+    very amaze

src/stripIndent/stripIndent.test.js

@@ -33,6 +33,16 @@ test('maintains deeper indentation', async (t) => {
   t.is(actual, expected)
 })
 
+test('maintains empty lines', async (t) => {
+  const expected = await readFromFixture(__dirname, 'maintainEmptyLines')
+  const actual = stripIndent`
+    wow such indent gone
+
+        very ${val}
+  `
+  t.is(actual, expected)
+})
+
 test('does nothing if there are no indents', async (t) => {
   const expected = 'wow such doge'
   const actual = stripIndent`wow such doge`

src/stripIndentTransformer/stripIndentTransformer.js

@@ -19,7 +19,7 @@ const stripIndentTransformer = (type = 'initial') => ({
       endResult = indent > 0 ? endResult.replace(regexp, '') : endResult
     } else if (type === 'all') {
       // remove all indentation from each line
-      endResult = endResult.replace(/(?:\n\s*)/g, '\n')
+      endResult = endResult.replace(/(?:\n[^\S\n]*)/g, '\n')
     } else {
       throw new Error(`Unknown type: ${type}`)
     }

src/stripIndents/fixtures/maintainEmptyLines.txt

@@ -0,0 +1,4 @@
+wow such indent gone
+very amaze
+
+foo bar baz

src/stripIndents/stripIndents.test.js

@@ -15,3 +15,14 @@ test('strips all indentation', async (t) => {
   `
   t.is(actual, expected)
 })
+
+test('maintains empty lines', async (t) => {
+  const expected = await readFromFixture(__dirname, 'maintainEmptyLines')
+  const actual = stripIndents`
+    wow such indent gone
+      very ${val}
+
+        foo bar baz
+  `
+  t.is(actual, expected)
+})