Add few smoke tests for patterns and refactoring

crates/ra_ide/src/completion/test_utils.rs

@@ -5,6 +5,8 @@ use crate::{
     mock_analysis::{analysis_and_position, single_file_with_position},
     CompletionItem,
 };
+use hir::Semantics;
+use ra_syntax::{AstNode, NodeOrToken, SyntaxElement, SyntaxToken};
 
 pub(crate) fn do_completion(code: &str, kind: CompletionKind) -> Vec<CompletionItem> {
     do_completion_with_options(code, kind, &CompletionConfig::default())
@@ -27,3 +29,15 @@ pub(crate) fn do_completion_with_options(
     kind_completions.sort_by_key(|c| c.label().to_owned());
     kind_completions
 }
+
+pub(crate) fn check_pattern_is_applicable(code: &str, check: fn(SyntaxElement) -> bool) {
+    let (analysis, pos) = single_file_with_position(code);
+    analysis
+        .with_db(|db| {
+            let sema = Semantics::new(db);
+            let original_file = sema.parse(pos.file_id);
+            let token = original_file.syntax().token_at_offset(pos.offset).left_biased().unwrap();
+            assert!(check(NodeOrToken::Token(token)));
+        })
+        .unwrap();
+}