Practice code coverage

Signed-off-by: Bruce <weichou1229@gmail.com>

playground/codecoverage/size.go

@@ -0,0 +1,17 @@
+package codecoverage
+
+func Size(a int) string {
+	switch {
+	case a < 0:
+		return "negative"
+	case a == 0:
+		return "zero"
+	case a < 10:
+		return "small"
+	case a < 100:
+		return "big"
+	case a < 1000:
+		return "huge"
+	}
+	return "enormous"
+}

playground/codecoverage/size_test.go

@@ -0,0 +1,26 @@
+package codecoverage
+
+import "testing"
+
+type Test struct {
+	in  int
+	out string
+}
+
+var tests = []Test{
+	{-1, "negative"},
+	{0, "zero"},
+	{5, "small"},
+	{99, "big"},
+	{100, "huge"},
+	{10001, "enormous"},
+}
+
+func TestSize(t *testing.T) {
+	for i, test := range tests {
+		size := Size(test.in)
+		if size != test.out {
+			t.Errorf("#%d: Size(%d)=%s; want %s", i, test.in, size, test.out)
+		}
+	}
+}