test: add hashmap tests

Hashmaps are still very primitive. These tests check that there are at
least no regressions in hashmap support.

testdata/map.go

@@ -0,0 +1,33 @@
+package main
+
+var testmap1 = map[string]int{"data": 3}
+var testmap2 = map[string]int{
+	"one":    1,
+	"two":    2,
+	"three":  3,
+	"four":   4,
+	"five":   5,
+	"six":    6,
+	"seven":  7,
+	"eight":  8,
+	"nine":   9,
+	"ten":    10,
+	"eleven": 11,
+	"twelve": 12,
+}
+
+func main() {
+	m := map[string]int{"answer": 42, "foo": 3}
+	readMap(m, "answer")
+	readMap(testmap1, "data")
+	readMap(testmap2, "three")
+	readMap(testmap2, "ten")
+}
+
+func readMap(m map[string]int, key string) {
+	println("map length:", len(m))
+	println("map read:", key, "=", m[key])
+	for k, v := range m {
+		println(" ", k, "=", v)
+	}
+}