Add some test cases to cover main

These don't include any asserts, but they do check panics

main_test.go

@@ -0,0 +1,122 @@
+package main
+
+import "testing"
+
+func TestCheckMonitors(t *testing.T) {
+	cases := []struct {
+		config      Config
+		expectPanic bool
+		name        string
+	}{
+		{
+			config:      Config{},
+			expectPanic: false,
+			name:        "Empty",
+		},
+		{
+			config: Config{
+				Monitors: []*Monitor{
+					&Monitor{
+						Name:    "Success",
+						Command: []string{"true"},
+					},
+				},
+			},
+			expectPanic: false,
+			name:        "Monitor success, no alerts",
+		},
+		{
+			config: Config{
+				Monitors: []*Monitor{
+					&Monitor{
+						Name:       "Failure",
+						Command:    []string{"false"},
+						AlertAfter: 1,
+					},
+					&Monitor{
+						Name:       "Failure",
+						Command:    []string{"false"},
+						AlertDown:  []string{"unknown"},
+						AlertAfter: 1,
+					},
+				},
+			},
+			expectPanic: false,
+			name:        "Monitor failure, no and unknown alerts",
+		},
+		{
+			config: Config{
+				Monitors: []*Monitor{
+					&Monitor{
+						Name:       "Success",
+						Command:    []string{"ls"},
+						alertCount: 1,
+					},
+					&Monitor{
+						Name:       "Success",
+						Command:    []string{"true"},
+						AlertUp:    []string{"unknown"},
+						alertCount: 1,
+					},
+				},
+			},
+			expectPanic: false,
+			name:        "Monitor recovery, no alerts",
+		},
+		{
+			config: Config{
+				Monitors: []*Monitor{
+					&Monitor{
+						Name:       "Failure",
+						Command:    []string{"false"},
+						AlertDown:  []string{"good"},
+						AlertAfter: 1,
+					},
+				},
+				Alerts: map[string]*Alert{
+					"good": &Alert{
+						Command: []string{"true"},
+					},
+				},
+			},
+			expectPanic: false,
+			name:        "Monitor failure, successful alert",
+		},
+		{
+			config: Config{
+				Monitors: []*Monitor{
+					&Monitor{
+						Name:       "Failure",
+						Command:    []string{"false"},
+						AlertDown:  []string{"bad"},
+						AlertAfter: 1,
+					},
+				},
+				Alerts: map[string]*Alert{
+					"bad": &Alert{
+						Name:    "bad",
+						Command: []string{"false"},
+					},
+				},
+			},
+			expectPanic: true,
+			name:        "Monitor failure, bad alert",
+		},
+	}
+
+	for _, c := range cases {
+		// Create new function so that deferred recovery can run at end of each test case
+		func() {
+			// Set up recover to catch panic
+			defer func() {
+				if r := recover(); r == nil {
+					if c.expectPanic {
+						t.Errorf("checkMonitors(%s): Expected panic, the code did not panic", c.name)
+					}
+				}
+			}()
+			c.config.Init()
+			checkMonitors(&c.config)
+		}()
+	}
+}