Add test file for lcm (#302)

Co-authored-by: Andrii Siriak <[email protected]>

Author: mbalayil

math/lcm/lcm_test.go

@@ -0,0 +1,44 @@
+package lcm
+
+import "testing"
+
+func TestLcm(t *testing.T) {
+	testCases := []struct {
+		name   string
+		a      int64
+		b      int64
+		output int64
+	}{
+		{
+			name:   "LCM of 1 & 5",
+			a:      1,
+			b:      5,
+			output: 5,
+		}, {
+			name:   "LCM of 2 & 5",
+			a:      2,
+			b:      5,
+			output: 10,
+		}, {
+			name:   "LCM of 5 & 10",
+			a:      10,
+			b:      5,
+			output: 10,
+		}, {
+			name:   "LCM of 5 & 5",
+			a:      5,
+			b:      5,
+			output: 5,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			actual_output := Lcm(tc.a, tc.b)
+			if actual_output != tc.output {
+				t.Errorf("Expected LCM of %d and %d is %d, but got %d", tc.a, tc.b, tc.output,
+					actual_output)
+			}
+		})
+	}
+}