tests/float/float_struct_e.py: Add specific test for struct 'e' type.

Signed-off-by: Damien George <damien@micropython.org>

tests/float/float_struct_e.py

@@ -0,0 +1,43 @@
+# Test struct pack/unpack with 'e' typecode.
+
+try:
+    import struct
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+test_values = (
+    1e-7,
+    2e-7,
+    1e-6,
+    1e-5,
+    1e-4,
+    1e-3,
+    1e-2,
+    0.1,
+    0,
+    1,
+    2,
+    4,
+    8,
+    10,
+    100,
+    1e3,
+    1e4,
+    6e4,
+    float("inf"),
+)
+
+for j in test_values:
+    for i in (j, -j):
+        x = struct.pack("<e", i)
+        v = struct.unpack("<e", x)[0]
+        print("%.7f %s %.15f %s" % (i, x, v, i == v))
+
+# In CPython, packing a float that doesn't fit into a half-float raises OverflowError.
+# But in MicroPython it does not, but rather stores the value as inf.
+# This test is here for coverage.
+try:
+    struct.pack("e", 1e15)
+except OverflowError:
+    pass