Add proverb exercise (#239)

Author: keiravillekode

config.json

@@ -327,6 +327,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "proverb",
+        "name": "Proverb",
+        "uuid": "d521aafa-57a9-4a2f-a32a-8e3efaf6f896",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "pythagorean-triplet",
         "name": "Pythagorean Triplet",

exercises/practice/proverb/.docs/instructions.md

@@ -0,0 +1,19 @@
+# Instructions
+
+For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
+
+Given a list of inputs, generate the relevant proverb.
+For example, given the list `["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]`, you will output the full text of this proverbial rhyme:
+
+```text
+For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.
+```
+
+Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content.
+No line of the output text should be a static, unchanging string; all should vary according to the input given.

exercises/practice/proverb/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "proverb.v"
+    ],
+    "test": [
+      "run_test.v"
+    ],
+    "example": [
+      ".meta/example.v"
+    ]
+  },
+  "blurb": "For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/For_Want_of_a_Nail"
+}

exercises/practice/proverb/.meta/example.v

@@ -0,0 +1,22 @@
+module main
+
+import strings
+
+fn recite(inputs []string) string {
+	if inputs.len == 0 {
+		return ''
+	}
+
+	mut builder := strings.new_builder(4000)
+	for i in 1 .. inputs.len {
+		builder.write_string('For want of a ')
+		builder.write_string(inputs[i - 1])
+		builder.write_string(' the ')
+		builder.write_string(inputs[i])
+		builder.write_string(' was lost.\n')
+	}
+	builder.write_string('And all for the want of a ')
+	builder.write_string(inputs[0])
+	builder.write_string('.')
+	return builder.str()
+}

exercises/practice/proverb/.meta/tests.toml

@@ -0,0 +1,21 @@
+# This is an auto-generated file. Regular comments will be removed when this
+# file is regenerated. Regenerating will not touch any manually added keys,
+# so comments can be added in a "comment" key.
+
+[e974b73e-7851-484f-8d6d-92e07fe742fc]
+description = "zero pieces"
+
+[2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4]
+description = "one piece"
+
+[d9d0a8a1-d933-46e2-aa94-eecf679f4b0e]
+description = "two pieces"
+
+[c95ef757-5e94-4f0d-a6cb-d2083f5e5a83]
+description = "three pieces"
+
+[433fb91c-35a2-4d41-aeab-4de1e82b2126]
+description = "full proverb"
+
+[c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7]
+description = "four pieces modernized"

exercises/practice/proverb/proverb.v

@@ -0,0 +1,4 @@
+module main
+
+fn recite(inputs []string) string {
+}

exercises/practice/proverb/run_test.v

@@ -0,0 +1,49 @@
+module main
+
+fn test_zero_pieces() {
+	strings := []string{}
+	expected := ''
+	assert recite(strings) == expected
+}
+
+fn test_one_piece() {
+	strings := ['nail']
+	expected := ('And all for the want of a nail.')
+	assert recite(strings) == expected
+}
+
+fn test_two_pieces() {
+	strings := ['nail', 'shoe']
+	expected := ('For want of a nail the shoe was lost.
+And all for the want of a nail.')
+	assert recite(strings) == expected
+}
+
+fn test_three_pieces() {
+	strings := ['nail', 'shoe', 'horse']
+	expected := ('For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+And all for the want of a nail.')
+	assert recite(strings) == expected
+}
+
+fn test_full_proverb() {
+	strings := ['nail', 'shoe', 'horse', 'rider', 'message', 'battle', 'kingdom']
+	expected := ('For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.')
+	assert recite(strings) == expected
+}
+
+fn test_four_pieces_modernized() {
+	strings := ['pin', 'gun', 'soldier', 'battle']
+	expected := ('For want of a pin the gun was lost.
+For want of a gun the soldier was lost.
+For want of a soldier the battle was lost.
+And all for the want of a pin.')
+	assert recite(strings) == expected
+}