Improving select docs (#839)

pkg/yqlib/operator_select_test.go

@@ -28,7 +28,17 @@ var selectOperatorScenarios = []expressionScenario{
 		expected:   []string{},
 	},
 	{
-		description: "Select elements from array",
+		description:    "Select elements from array with regular expression",
+		subdescription: "See more regular expression examples under the `string` operator docs.",
+		document:       `[this_0, not_this, nor_0_this, thisTo_4]`,
+		expression:     `.[] | select(test("[a-zA-Z]+_[0-9]$"))`,
+		expected: []string{
+			"D0, P[0], (!!str)::this_0\n",
+			"D0, P[3], (!!str)::thisTo_4\n",
+		},
+	},
+	{
+		description: "Select elements from array using wildcard prefix",
 		document:    `[cat,goat,dog]`,
 		expression:  `.[] | select(. == "*at")`,
 		expected: []string{
@@ -36,6 +46,25 @@ var selectOperatorScenarios = []expressionScenario{
 			"D0, P[1], (!!str)::goat\n",
 		},
 	},
+	{
+		description: "Select elements from array using wildcard suffix",
+		document:    `[go-kart,goat,dog]`,
+		expression:  `.[] | select(. == "go*")`,
+		expected: []string{
+			"D0, P[0], (!!str)::go-kart\n",
+			"D0, P[1], (!!str)::goat\n",
+		},
+	},
+	{
+		description: "Select elements from array using wildcard prefix and suffix",
+		document:    `[ago, go, meow, going]`,
+		expression:  `.[] | select(. == "*go*")`,
+		expected: []string{
+			"D0, P[0], (!!str)::ago\n",
+			"D0, P[1], (!!str)::go\n",
+			"D0, P[3], (!!str)::going\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   "a: hello",
@@ -69,9 +98,27 @@ var selectOperatorScenarios = []expressionScenario{
 			"D0, P[a 1], (!!str)::goat\n"},
 	},
 	{
-		description: "Select and update matching values in map",
-		document:    `a: { things: cat, bob: goat, horse: dog }`,
-		expression:  `(.a.[] | select(. == "*at")) |= "rabbit"`,
+		description: "Select items from a map",
+		document:    `{ things: cat, bob: goat, horse: dog }`,
+		expression:  `.[] | select(. == "cat" or test("og$"))`,
+		expected: []string{
+			"D0, P[things], (!!str)::cat\n",
+			"D0, P[horse], (!!str)::dog\n",
+		},
+	},
+	{
+		description: "Use select + with_entries to filter map keys",
+		document:    `{name: bob, legs: 2, game: poker}`,
+		expression:  `with_entries(select(.key | test("ame$")))`,
+		expected: []string{
+			"D0, P[], (!!map)::name: bob\ngame: poker\n",
+		},
+	},
+	{
+		description:    "Select multiple items in a map and update",
+		subdescription: "Note the brackets around the entire LHS.",
+		document:       `a: { things: cat, bob: goat, horse: dog }`,
+		expression:     `(.a.[] | select(. == "cat" or . == "goat")) |= "rabbit"`,
 		expected: []string{
 			"D0, P[], (doc)::a: {things: rabbit, bob: rabbit, horse: dog}\n",
 		},