feat(std/node): add string_decoder (#6638)

1 files changed, 117 insertions, 0 deletions

diff --git a/std/node/string_decoder_test.ts b/std/node/string_decoder_test.ts
new file mode 100644
index 000000000..69bb8402a
--- /dev/null
+++ b/std/node/string_decoder_test.ts
@@ -0,0 +1,117 @@
+import { assertEquals } from "../testing/asserts.ts";
+import Buffer from "./buffer.ts";
+import { StringDecoder } from "./string_decoder.ts";
+
+Deno.test({
+  name: "String decoder is encoding utf8 correctly",
+  fn() {
+    let decoder;
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(decoder.write(Buffer.from("E1", "hex")), "");
+    assertEquals(decoder.end(), "\ufffd");
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(decoder.write(Buffer.from("E18B", "hex")), "");
+    assertEquals(decoder.end(), "\ufffd");
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(decoder.write(Buffer.from("\ufffd")), "\ufffd");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(
+      decoder.write(Buffer.from("\ufffd\ufffd\ufffd")),
+      "\ufffd\ufffd\ufffd"
+    );
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(decoder.write(Buffer.from("EFBFBDE2", "hex")), "\ufffd");
+    assertEquals(decoder.end(), "\ufffd");
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(decoder.write(Buffer.from("F1", "hex")), "");
+    assertEquals(decoder.write(Buffer.from("41F2", "hex")), "\ufffdA");
+    assertEquals(decoder.end(), "\ufffd");
+
+    decoder = new StringDecoder("utf8");
+    assertEquals(decoder.text(Buffer.from([0x41]), 2), "");
+  },
+});
+
+Deno.test({
+  name: "String decoder is encoding base64 correctly",
+  fn() {
+    let decoder;
+
+    decoder = new StringDecoder("base64");
+    assertEquals(decoder.write(Buffer.from("E1", "hex")), "4Q==");
+    assertEquals(decoder.end(), "4QAA");
+
+    decoder = new StringDecoder("base64");
+    assertEquals(decoder.write(Buffer.from("E18B", "hex")), "4Ys=");
+    assertEquals(decoder.end(), "4YsA");
+
+    decoder = new StringDecoder("base64");
+    assertEquals(decoder.write(Buffer.from("\ufffd")), "77+9");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("base64");
+    assertEquals(
+      decoder.write(Buffer.from("\ufffd\ufffd\ufffd")),
+      "77+977+977+9"
+    );
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("base64");
+    assertEquals(decoder.write(Buffer.from("EFBFBDE2", "hex")), "77+94g==");
+    assertEquals(decoder.end(), "4gAA");
+
+    decoder = new StringDecoder("base64");
+    assertEquals(decoder.write(Buffer.from("F1", "hex")), "8Q==");
+    assertEquals(decoder.write(Buffer.from("41F2", "hex")), "8UHy");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("base64");
+    assertEquals(decoder.text(Buffer.from([0x41]), 2), "QQ==");
+  },
+});
+
+Deno.test({
+  name: "String decoder is encoding hex correctly",
+  fn() {
+    let decoder;
+
+    decoder = new StringDecoder("hex");
+    assertEquals(decoder.write(Buffer.from("E1", "hex")), "e1");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("hex");
+    assertEquals(decoder.write(Buffer.from("E18B", "hex")), "e18b");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("hex");
+    assertEquals(decoder.write(Buffer.from("\ufffd")), "efbfbd");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("hex");
+    assertEquals(
+      decoder.write(Buffer.from("\ufffd\ufffd\ufffd")),
+      "efbfbdefbfbdefbfbd"
+    );
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("hex");
+    assertEquals(decoder.write(Buffer.from("EFBFBDE2", "hex")), "efbfbde2");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("hex");
+    assertEquals(decoder.write(Buffer.from("F1", "hex")), "f1");
+    assertEquals(decoder.write(Buffer.from("41F2", "hex")), "41f2");
+    assertEquals(decoder.end(), "");
+
+    decoder = new StringDecoder("hex");
+    assertEquals(decoder.text(Buffer.from([0x41]), 2), "");
+  },
+});