Add test for --no-html-source flag

tests/rustdoc/html-no-source.rs

@@ -0,0 +1,30 @@
+// compile-flags: -Zunstable-options --html-no-source
+
+// This test ensures that the `--html-no-source` flag disables
+// the creation of the `src` folder.
+
+#![feature(staged_api)]
+#![stable(feature = "bar", since = "1.0")]
+#![crate_name = "foo"]
+
+// Ensures that there is no items in the corresponding "src" folder.
+// @files 'src/foo' '[]'
+
+// @has foo/fn.foo.html
+// @has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · '
+// @!has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · source · '
+#[stable(feature = "bar", since = "1.0")]
+pub fn foo() {}
+
+// @has foo/struct.Bar.html
+// @has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · '
+// @!has - '//div[@class="main-heading"]/*[@class="out-of-band"]' '1.0 · source · '
+#[stable(feature = "bar", since = "1.0")]
+pub struct Bar;
+
+impl Bar {
+    // @has - '//*[@id="method.bar"]/*[@class="since rightside"]' '2.0'
+    // @!has - '//*[@id="method.bar"]/*[@class="rightside"]' '2.0 ·'
+    #[stable(feature = "foobar", since = "2.0")]
+    pub fn bar() {}
+}