Add test for incremental parsing

marijnh · marijnh · commit 1e054dec8309 · 2021-02-17T14:50:40.000+01:00
diff --git a/test/test-incremental.js b/test/test-incremental.js
@@ -0,0 +1,33 @@
+import {parser} from "../dist/index.es.js"
+import {fileTests} from "lezer-generator/dist/test"
+import {Tree, TreeFragment} from "lezer-tree"
+
+describe("Incremental parsing", () => {
+  // See https://github.com/codemirror/codemirror.next/issues/394
+  it("doesn't reuse statements in the wrong body", () => {
+    let input = `class StreamWriter:
+    def __init__(self):
+        pass
+
+def a():
+    pass
+
+def b(self):
+    """ ${"big block comment to fill up the reuse size quota\n  ".repeat(150)} """
+    pass
+`
+    let ast = parser.parse(input)
+    let at = input.indexOf("pass")
+    input = input.slice(0, at) + " " + input.slice(at)
+    let cache = TreeFragment.applyChanges(TreeFragment.addTree(ast), [{fromA: at, toA: at, fromB: at, toB: at + 1}])
+    let ast2 = parser.parse(input, 0, {fragments: cache})
+    if (ast2.toString() != ast.toString()) throw new Error("Malformed tree")
+
+    let lastFunc = ast => {
+      let cur = ast.cursor(ast.length)
+      while (cur.type.name != "FunctionDefinition") cur.prev()
+      return cur.tree
+    }
+    if (lastFunc(ast) != lastFunc(ast2)) throw new Error("No reuse")
+  })
+})
