diff --git a/src/test/run-pass/estr-internal.rs b/src/test/run-pass/estr-internal.rs
new file mode 100644
index 000000000000..8e9debbdfdec
--- /dev/null
+++ b/src/test/run-pass/estr-internal.rs
@@ -0,0 +1,9 @@
+// xfail-test
+fn main() {
+    let x : str/5 = "hello"/5;
+    let y : str/5 = "there"/_;
+    let mut z = "thing"/_;
+    z = x;
+    assert z[1] == 'h' as u8;
+    assert z[4] == 'g' as u8;
+}
diff --git a/src/test/run-pass/estr-shared.rs b/src/test/run-pass/estr-shared.rs
new file mode 100644
index 000000000000..6fc0f296d8d2
--- /dev/null
+++ b/src/test/run-pass/estr-shared.rs
@@ -0,0 +1,4 @@
+// xfail-test
+fn main() {
+    let x : str/@ = "hello"/@;
+}
diff --git a/src/test/run-pass/estr-slice.rs b/src/test/run-pass/estr-slice.rs
new file mode 100644
index 000000000000..bf727908e9e6
--- /dev/null
+++ b/src/test/run-pass/estr-slice.rs
@@ -0,0 +1,8 @@
+// xfail-test
+fn main() {
+    let x : str/& = "hello";
+    let mut y = "there";
+    y = x;
+    assert y[1] == 'h' as u8;
+    assert y[4] == 'e' as u8;
+}
\ No newline at end of file
diff --git a/src/test/run-pass/estr-uniq.rs b/src/test/run-pass/estr-uniq.rs
new file mode 100644
index 000000000000..178f1c8c26be
--- /dev/null
+++ b/src/test/run-pass/estr-uniq.rs
@@ -0,0 +1,4 @@
+// xfail-test
+fn main() {
+    let x : str/~ = "hello"/~;
+}