Add support for the --load-path flag (#251)

Partially addresses #105

CHANGELOG.md

@@ -3,6 +3,9 @@
 * Add support for importing an `_index.scss` or `_index.sass` file when
   importing a directory.
 
+* Add a `--load-path` command-line option (alias `-I`) for passing additional
+  paths to search for Sass files to import.
+
 ### Node JS API
 
 * Import URLs passed to importers are no longer normalized. For example, if a

lib/src/executable.dart

@@ -17,8 +17,16 @@ main(List<String> args) async {
   var argParser = new ArgParser(allowTrailingOptions: true)
     ..addOption('precision', hide: true)
     ..addFlag('stdin', help: 'Read the stylesheet from stdin.')
+    ..addOption('load-path',
+        abbr: 'I',
+        valueHelp: 'PATH',
+        help: 'A path to use when resolving imports.\n'
+            'May be passed multiple times.',
+        allowMultiple: true,
+        splitCommas: false)
     ..addOption('style',
         abbr: 's',
+        valueHelp: 'NAME',
         help: 'Output style.',
         allowed: ['expanded', 'compressed'],
         defaultsTo: 'expanded')
@@ -62,19 +70,23 @@ main(List<String> args) async {
   var style = options['style'] == 'compressed'
       ? OutputStyle.compressed
       : OutputStyle.expanded;
+  var loadPaths = options['load-path'] as List<String>;
   var asynchronous = options['async'] as bool;
   try {
     String css;
     if (stdinFlag) {
-      css = await _compileStdin(style: style, asynchronous: asynchronous);
+      css = await _compileStdin(
+          style: style, loadPaths: loadPaths, asynchronous: asynchronous);
     } else {
       var input = options.rest.first;
       if (input == '-') {
-        css = await _compileStdin(style: style, asynchronous: asynchronous);
+        css = await _compileStdin(
+            style: style, loadPaths: loadPaths, asynchronous: asynchronous);
       } else if (asynchronous) {
-        css = await compileAsync(input, color: color, style: style);
+        css = await compileAsync(input,
+            color: color, style: style, loadPaths: loadPaths);
       } else {
-        css = compile(input, color: color, style: style);
+        css = compile(input, color: color, style: style, loadPaths: loadPaths);
       }
     }
 
@@ -138,14 +150,18 @@ Future<String> _loadVersion() async {
 
 /// Compiles Sass from standard input and returns the result.
 Future<String> _compileStdin(
-    {bool color: false, OutputStyle style, bool asynchronous: false}) async {
+    {bool color: false,
+    OutputStyle style,
+    List<String> loadPaths,
+    bool asynchronous: false}) async {
   var text = await readStdin();
   var importer = new FilesystemImporter('.');
   if (asynchronous) {
     return await compileStringAsync(text,
-        color: color, style: style, importer: importer);
+        color: color, style: style, importer: importer, loadPaths: loadPaths);
   } else {
-    return compileString(text, color: color, style: style, importer: importer);
+    return compileString(text,
+        color: color, style: style, importer: importer, loadPaths: loadPaths);
   }
 }
 

test/cli_shared.dart

@@ -48,6 +48,81 @@ void sharedTests(Future<TestProcess> runSass(Iterable<String> arguments)) {
     await sass.shouldExit(0);
   });
 
+  group("can import files", () {
+    test("relative to the entrypoint", () async {
+      await d.file("test.scss", "@import 'dir/test'").create();
+
+      await d.dir("dir", [d.file("test.scss", "a {b: 1 + 2}")]).create();
+
+      var sass = await runSass(["test.scss", "test.css"]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "a {",
+            "  b: 3;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+
+    test("from the load path", () async {
+      await d.file("test.scss", "@import 'test2'").create();
+
+      await d.dir("dir", [d.file("test2.scss", "a {b: c}")]).create();
+
+      var sass = await runSass(["--load-path", "dir", "test.scss", "test.css"]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "a {",
+            "  b: c;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+
+    test("relative in preference to from the load path", () async {
+      await d.file("test.scss", "@import 'test2'").create();
+      await d.file("test2.scss", "x {y: z}").create();
+
+      await d.dir("dir", [d.file("test2.scss", "a {b: c}")]).create();
+
+      var sass = await runSass(["--load-path", "dir", "test.scss", "test.css"]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "x {",
+            "  y: z;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+
+    test("in load path order", () async {
+      await d.file("test.scss", "@import 'test2'").create();
+
+      await d.dir("dir1", [d.file("test2.scss", "a {b: c}")]).create();
+      await d.dir("dir2", [d.file("test2.scss", "x {y: z}")]).create();
+
+      var sass = await runSass([
+        "--load-path",
+        "dir2",
+        "--load-path",
+        "dir1",
+        "test.scss",
+        "test.css"
+      ]);
+      expect(
+          sass.stdout,
+          emitsInOrder([
+            "x {",
+            "  y: z;",
+            "}",
+          ]));
+      await sass.shouldExit(0);
+    });
+  });
+
   test("compiles from stdin with --stdin", () async {
     var sass = await runSass(["--stdin"]);
     sass.stdin.writeln("a {b: 1 + 2}");