1 files changed, 81 insertions, 0 deletions
diff --git a/src/test/scala/chisel3/internal/NamespaceSpec.scala b/src/test/scala/chisel3/internal/NamespaceSpec.scala
new file mode 100644
index 00000000..fd808ff0
--- /dev/null
+++ b/src/test/scala/chisel3/internal/NamespaceSpec.scala
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: Apache-2.0
+
+package chisel3.internal
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers._
+
+class NamespaceSpec extends AnyFlatSpec {
+  behavior.of("Namespace")
+
+  they should "support basic disambiguation" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("x") should be("x")
+    name("x") should be("x_1")
+    name("x") should be("x_2")
+  }
+
+  they should "support explicit <prefix>_# names before <prefix> names" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("x_1") should be("x_1")
+    name("x_2") should be("x_2")
+    name("x") should be("x")
+    name("x") should be("x_3")
+  }
+
+  they should "support explicit <prefix>_# names in the middle of <prefix> names" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("x") should be("x")
+    name("x") should be("x_1")
+    name("x_1") should be("x_1_1")
+    name("x_2") should be("x_2")
+    name("x") should be("x_3")
+  }
+
+  // For some reason, multi-character names tickled a different failure mode than single character
+  they should "support explicit <prefix>_# names in the middle of longer <prefix> names" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("foo") should be("foo")
+    name("foo") should be("foo_1")
+    name("foo_1") should be("foo_1_1")
+    name("foo_2") should be("foo_2")
+    name("foo") should be("foo_3")
+  }
+
+  they should "support collisions in recursively growing names" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("x") should be("x")
+    name("x") should be("x_1")
+    name("x_1") should be("x_1_1")
+    name("x_1") should be("x_1_2")
+    name("x_1_1") should be("x_1_1_1")
+    name("x_1_1") should be("x_1_1_2")
+  }
+
+  they should "support collisions in recursively shrinking names" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("x_1_1") should be("x_1_1")
+    name("x_1_1") should be("x_1_1_1")
+    name("x_1") should be("x_1")
+    name("x_1") should be("x_1_2")
+    name("x") should be("x")
+    name("x") should be("x_2")
+  }
+
+  // The namespace never generates names with _0 so it's actually a false collision case
+  they should "properly handle false collisions with signals ending in _0" in {
+    val namespace = Namespace.empty
+    val name = namespace.name(_, false)
+    name("x") should be("x")
+    name("x") should be("x_1")
+    name("x_0") should be("x_0")
+    name("x") should be("x_2")
+    name("x_0") should be("x_0_1")
+  }
+}