Added subtract operator (numbers only)

pkg/yqlib/operator_subtract_test.go

@@ -0,0 +1,50 @@
+package yqlib
+
+import (
+	"testing"
+)
+
+var subtractOperatorScenarios = []expressionScenario{
+	{
+		description:    "Number subtraction - float",
+		subdescription: "If the lhs or rhs are floats then the expression will be calculated with floats.",
+		document:       `{a: 3, b: 4.5}`,
+		expression:     `.a = .a - .b`,
+		expected: []string{
+			"D0, P[], (doc)::{a: -1.5, b: 4.5}\n",
+		},
+	},
+	{
+		description:    "Number subtraction - float",
+		subdescription: "If the lhs or rhs are floats then the expression will be calculated with floats.",
+		document:       `{a: 3, b: 4.5}`,
+		expression:     `.a = .a - .b`,
+		expected: []string{
+			"D0, P[], (doc)::{a: -1.5, b: 4.5}\n",
+		},
+	},
+	{
+		description:    "Number subtraction - int",
+		subdescription: "If both the lhs and rhs are ints then the expression will be calculated with ints.",
+		document:       `{a: 3, b: 4}`,
+		expression:     `.a = .a - .b`,
+		expected: []string{
+			"D0, P[], (doc)::{a: -1, b: 4}\n",
+		},
+	},
+	{
+		description: "Decrement numbers",
+		document:    `{a: 3, b: 5}`,
+		expression:  `.[] -= 1`,
+		expected: []string{
+			"D0, P[], (doc)::{a: 2, b: 4}\n",
+		},
+	},
+}
+
+func TestSubtractOperatorScenarios(t *testing.T) {
+	for _, tt := range subtractOperatorScenarios {
+		testScenario(t, &tt)
+	}
+	documentScenarios(t, "Subtract", subtractOperatorScenarios)
+}