Add a new trim command to trim whitespaces in the current line (#4772)

tests_integration/__tests__/doc-mark-as-root.js

@@ -0,0 +1,38 @@
+"use strict";
+
+const prettier = require("prettier/local");
+const docPrinter = prettier.doc.printer;
+const docBuilders = prettier.doc.builders;
+
+const printDocToString = docPrinter.printDocToString;
+const concat = docBuilders.concat;
+const hardline = docBuilders.hardline;
+const literalline = docBuilders.literalline;
+const trim = docBuilders.trim;
+const indent = docBuilders.indent;
+const markAsRoot = docBuilders.markAsRoot;
+
+describe("markAsRoot", () => {
+  test.each([
+    [
+      "with hardline will insert a newline with current indentation",
+      concat([indent(markAsRoot(indent(hardline))), "123"]),
+      "\n    123"
+    ],
+    [
+      "with literalline will insert a newline with root indentation",
+      concat([indent(markAsRoot(indent(literalline))), "123"]),
+      "\n  123"
+    ],
+    [
+      "followed by trim will trims up to the the first column, ignoring indented root",
+      concat([indent(markAsRoot(indent(literalline))), trim, "123"]),
+      "\n123"
+    ]
+  ])("%s", (_, doc, expected) => {
+    const result = printDocToString(doc, { printWidth: 80, tabWidth: 2 });
+
+    expect(result).toBeDefined();
+    expect(result.formatted).toEqual(expected);
+  });
+});

tests_integration/__tests__/doc-trim.js

@@ -0,0 +1,59 @@
+"use strict";
+
+const prettier = require("prettier/local");
+const docPrinter = prettier.doc.printer;
+const docBuilders = prettier.doc.builders;
+
+const printDocToString = docPrinter.printDocToString;
+const concat = docBuilders.concat;
+const line = docBuilders.line;
+const trim = docBuilders.trim;
+const group = docBuilders.group;
+const indent = docBuilders.indent;
+
+// These tests don't use `runPrettier` because `trim` is not used by any
+// bundled parser (only third-party plugins).
+
+describe("trim", () => {
+  test.each([
+    ["trims the current line", group(concat(["hello    ", trim])), "hello"],
+    [
+      "trims existing indentation",
+      group(
+        concat([
+          "function()",
+          line,
+          "{",
+          indent(
+            concat([
+              line,
+              group(concat([trim, "#if DEBUG"])),
+              line,
+              "alert(42);",
+              line,
+              group(concat([trim, "#endif"]))
+            ])
+          ),
+          line,
+          "}"
+        ])
+      ),
+      `function()
+{
+#if DEBUG
+  alert(42);
+#endif
+}`
+    ],
+    [
+      "ignores trimmed characters when fitting the line",
+      group(concat(["hello  ", "  ", trim, line, "world!"])),
+      "hello world!"
+    ]
+  ])("%s", (_, doc, expected) => {
+    const result = printDocToString(doc, { printWidth: 12, tabWidth: 2 });
+
+    expect(result).toBeDefined();
+    expect(result.formatted).toEqual(expected);
+  });
+});