2 files changed, 80 insertions, 0 deletions
diff --git a/cli/tests/unit/streams_internal_test.ts b/cli/tests/unit/streams_internal_test.ts
new file mode 100644
index 000000000..f324da194
--- /dev/null
+++ b/cli/tests/unit/streams_internal_test.ts
@@ -0,0 +1,79 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { unitTest, assertThrows } from "./test_util.ts";
+
+unitTest(function streamReadableHwmError() {
+  const invalidHwm = [NaN, Number("NaN"), {}, -1, "two"];
+  for (const highWaterMark of invalidHwm) {
+    assertThrows(
+      () => {
+        new ReadableStream<number>(
+          undefined,
+          // @ts-ignore
+          { highWaterMark }
+        );
+      },
+      RangeError,
+      "highWaterMark must be a positive number or Infinity.  Received:"
+    );
+  }
+
+  assertThrows(() => {
+    new ReadableStream<number>(
+      undefined,
+      // @ts-ignore
+      { highWaterMark: Symbol("hwk") }
+    );
+  }, TypeError);
+});
+
+unitTest(function streamWriteableHwmError() {
+  const invalidHwm = [NaN, Number("NaN"), {}, -1, "two"];
+  for (const highWaterMark of invalidHwm) {
+    assertThrows(
+      () => {
+        new WritableStream(
+          undefined,
+          // @ts-ignore
+          new CountQueuingStrategy({ highWaterMark })
+        );
+      },
+      RangeError,
+      "highWaterMark must be a positive number or Infinity.  Received:"
+    );
+  }
+
+  assertThrows(() => {
+    new WritableStream(
+      undefined,
+      // @ts-ignore
+      new CountQueuingStrategy({ highWaterMark: Symbol("hwmk") })
+    );
+  }, TypeError);
+});
+
+unitTest(function streamTransformHwmError() {
+  const invalidHwm = [NaN, Number("NaN"), {}, -1, "two"];
+  for (const highWaterMark of invalidHwm) {
+    assertThrows(
+      () => {
+        new TransformStream(
+          undefined,
+          undefined,
+          // @ts-ignore
+          { highWaterMark }
+        );
+      },
+      RangeError,
+      "highWaterMark must be a positive number or Infinity.  Received:"
+    );
+  }
+
+  assertThrows(() => {
+    new TransformStream(
+      undefined,
+      undefined,
+      // @ts-ignore
+      { highWaterMark: Symbol("hwmk") }
+    );
+  }, TypeError);
+});
diff --git a/cli/tests/unit/unit_tests.ts b/cli/tests/unit/unit_tests.ts
index 7327bcc05..515da9f4a 100644
--- a/cli/tests/unit/unit_tests.ts
+++ b/cli/tests/unit/unit_tests.ts
@@ -52,6 +52,7 @@ import "./request_test.ts";
 import "./resources_test.ts";
 import "./signal_test.ts";
 import "./stat_test.ts";
+import "./streams_internal_test.ts";
 import "./streams_piping_test.ts";
 import "./streams_transform_test.ts";
 import "./streams_writable_test.ts";