Fixing readonly ops not to modify context when paths dont exist

pkg/yqlib/operator_unique_test.go

@@ -0,0 +1,65 @@
+package yqlib
+
+import (
+	"testing"
+)
+
+var uniqueOperatorScenarios = []expressionScenario{
+	{
+		description: "Unique array of scalars (string/numbers)",
+		document:    `[1,2,3,2]`,
+		expression:  `unique`,
+		expected: []string{
+			"D0, P[], (!!seq)::- 1\n- 2\n- 3\n",
+		},
+	},
+	{
+		description:    "Unique nulls",
+		subdescription: "Unique works on the node value, so it considers different representations of nulls to be different",
+		document:       `[~,null, ~, null]`,
+		expression:     `unique`,
+		expected: []string{
+			"D0, P[], (!!seq)::- ~\n- null\n",
+		},
+	},
+	{
+		description:    "Unique all nulls",
+		subdescription: "Run against the node tag to unique all the nulls",
+		document:       `[~,null, ~, null]`,
+		expression:     `unique_by(tag)`,
+		expected: []string{
+			"D0, P[], (!!seq)::- ~\n",
+		},
+	},
+	{
+		description: "Unique array object fields",
+		document:    `[{name: harry, pet: cat}, {name: billy, pet: dog}, {name: harry, pet: dog}]`,
+		expression:  `unique_by(.name)`,
+		expected: []string{
+			"D0, P[], (!!seq)::- {name: harry, pet: cat}\n- {name: billy, pet: dog}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `[{name: harry, pet: cat}, {pet: fish}, {name: harry, pet: dog}]`,
+		expression: `unique_by(.name)`,
+		expected: []string{
+			"D0, P[], (!!seq)::- {name: harry, pet: cat}\n- {pet: fish}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `[{name: harry, pet: cat}, {pet: fish}, {name: harry, pet: dog}]`,
+		expression: `unique_by(.cat.dog)`,
+		expected: []string{
+			"D0, P[], (!!seq)::- {name: harry, pet: cat}\n",
+		},
+	},
+}
+
+func TestUniqueOperatorScenarios(t *testing.T) {
+	for _, tt := range uniqueOperatorScenarios {
+		testScenario(t, &tt)
+	}
+	documentScenarios(t, "Unique", uniqueOperatorScenarios)
+}