diff --git a/cue/interpreter/wasm/testdata/cue/default.txtar b/cue/interpreter/wasm/testdata/cue/default.txtar
new file mode 100644
index 000000000..14e24a8fd
--- /dev/null
+++ b/cue/interpreter/wasm/testdata/cue/default.txtar
@@ -0,0 +1,16 @@
+# Check that default values are resolved correctly.
+
+exec cue eval -E --out cue
+cmp stdout out/wasm
+
+-- a.cue --
+@extern("wasm")
+package p
+
+add: _ @extern("basic.wasm", abi=c, sig="func(int64, int64): int64")
+
+x0: add(*1 | string, *2 | string)
+-- basic.wasm --
+-- out/wasm --
+add: add
+x0:  3
\ No newline at end of file
diff --git a/cue/testdata/builtins/default.txtar b/cue/testdata/builtins/default.txtar
new file mode 100644
index 000000000..0d2c6ca6d
--- /dev/null
+++ b/cue/testdata/builtins/default.txtar
@@ -0,0 +1,59 @@
+-- in.cue --
+import (
+	"list"
+	"strings"
+	"text/template"
+)
+
+Len: len(*[1, 2, 3] | 0)
+Close: close(*{} | 0)
+And: and(*[1, 1] | int)
+Or: or(*[1, 1] | int)
+Div: div(*5 | string, 2)
+Mod: mod(*5 | string, 2)
+Quo: quo(*5 | string, 2)
+Rem: rem(*5 | string, 2)
+-- out/compile --
+--- in.cue
+{
+  Len: len((*[
+    1,
+    2,
+    3,
+  ]|0))
+  Close: close((*{}|0))
+  And: and((*[
+    1,
+    1,
+  ]|int))
+  Or: or((*[
+    1,
+    1,
+  ]|int))
+  Div: div((*5|string), 2)
+  Mod: mod((*5|string), 2)
+  Quo: quo((*5|string), 2)
+  Rem: rem((*5|string), 2)
+}
+-- out/eval/stats --
+Leaks:  0
+Freed:  45
+Reused: 40
+Allocs: 5
+Retain: 0
+
+Unifications: 25
+Conjuncts:    52
+Disjuncts:    45
+-- out/eval --
+(struct){
+  Len: (int){ 3 }
+  Close: (struct){
+  }
+  And: (int){ 1 }
+  Or: (int){ 1 }
+  Div: (int){ 2 }
+  Mod: (int){ 1 }
+  Quo: (int){ 2 }
+  Rem: (int){ 1 }
+}
diff --git a/pkg/net/testdata/toip4.txtar b/pkg/net/testdata/toip4.txtar
new file mode 100644
index 000000000..d6af7156a
--- /dev/null
+++ b/pkg/net/testdata/toip4.txtar
@@ -0,0 +1,21 @@
+-- in.cue --
+import "net"
+
+fail: {
+    t1: net.ToIP4(1 | 2)
+    t2: net.ToIP4(string)
+}
+
+ok: {
+    t1: net.ToIP4(*"4.4.4.4" | "8.8.8.8")
+}
+-- out/net --
+import "net"
+
+fail: {
+	t1: net.ToIP4(1 | 2)
+	t2: net.ToIP4(string)
+}
+ok: {
+	t1: [4, 4, 4, 4]
+}
diff --git a/pkg/strings/testdata/join.txtar b/pkg/strings/testdata/join.txtar
new file mode 100644
index 000000000..72feb5d71
--- /dev/null
+++ b/pkg/strings/testdata/join.txtar
@@ -0,0 +1,6 @@
+-- in.cue --
+import "strings"
+
+disjunctDefault:  strings.Join(*["Hello", "World!"] | int, " ")
+-- out/strings --
+disjunctDefault: "Hello World!"