Migrate run-make/rustdoc-themes to new rmake

Author: GuillaumeGomez

tests/run-make/rustdoc-themes/Makefile

@@ -0,0 +1,31 @@
+// Test that rustdoc will properly load in a theme file and display it in the theme selector.
+
+use run_make_support::{htmldocck, rustdoc, source_path, tmp_dir};
+
+fn main() {
+    let out_dir = tmp_dir().join("rustdoc-themes");
+    let test_css = out_dir.join("test.css");
+
+    let no_script = std::fs::read_to_string(source_path().join("src/librustdoc/html/static/css/noscript.css")).unwrap();
+
+    let mut test_content = String::new();
+    let mut found_begin_light = false;
+    for line in no_script.split('\n') {
+        if line == "/* Begin theme: light */" {
+            found_begin_light = true;
+        } else if line == "/* End theme: light */" {
+            break;
+        } else if found_begin_light {
+            test_content.push_str(line);
+            test_content.push('\n');
+        }
+    }
+    assert!(!test_content.is_empty());
+    std::fs::create_dir_all(&out_dir).unwrap();
+    std::fs::write(&test_css, test_content).unwrap();
+
+    rustdoc().output(&out_dir).input("foo.rs").arg("--theme").arg(&test_css).run();
+    htmldocck().arg(out_dir).arg("foo.rs").status()
+    .unwrap()
+    .success();
+}