Initial upload

go/isbn-verifier/.exercism/config.json

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+{
+  "blurb": "Check if a given string is a valid ISBN-10 number.",
+  "authors": [
+    "creaaa"
+  ],
+  "contributors": [
+    "bitfield",
+    "ekingery",
+    "ferhatelmas",
+    "h311ion",
+    "hilary",
+    "kytrinyx",
+    "leenipper",
+    "sebito91",
+    "tinsch"
+  ],
+  "files": {
+    "solution": [
+      "isbn_verifier.go"
+    ],
+    "test": [
+      "isbn_verifier_test.go"
+    ],
+    "example": [
+      ".meta/example.go"
+    ],
+    "editor": [
+      "cases_test.go"
+    ]
+  },
+  "source": "Converting a string into a number and some basic processing utilizing a relatable real world example.",
+  "source_url": "https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation"
+}

go/isbn-verifier/.exercism/metadata.json

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+{"track":"go","exercise":"isbn-verifier","id":"c2a9f9ef655f45b1b42a5530b24252d1","url":"https://exercism.org/tracks/go/exercises/isbn-verifier","handle":"halfdan","is_requester":true,"auto_approve":false}

go/isbn-verifier/HELP.md

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+# Help
+
+## Running the tests
+
+To run the tests run the command `go test` from within the exercise directory.
+
+If the test suite contains benchmarks, you can run these with the `--bench` and `--benchmem`
+flags:
+
+    go test -v --bench . --benchmem
+
+Keep in mind that each reviewer will run benchmarks on a different machine, with
+different specs, so the results from these benchmark tests may vary.
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit isbn_verifier.go` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Go track's documentation](https://exercism.org/docs/tracks/go)
+- [Exercism's support channel on gitter](https://gitter.im/exercism/support)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+To get help if you're having trouble, you can use one of the following resources:
+
+- [How to Write Go Code](https://golang.org/doc/code.html)
+- [Effective Go](https://golang.org/doc/effective_go.html)
+- [Go Resources](http://golang.org/help)
+- [StackOverflow](http://stackoverflow.com/questions/tagged/go)

go/isbn-verifier/README.md

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+# Isbn Verifier
+
+Welcome to Isbn Verifier on Exercism's Go Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+The [ISBN-10 verification process](https://en.wikipedia.org/wiki/International_Standard_Book_Number) is used to validate book identification
+numbers. These normally contain dashes and look like: `3-598-21508-8`
+
+## ISBN
+
+The ISBN-10 format is 9 digits (0 to 9) plus one check character (either a digit or an X only). In the case the check character is an X, this represents the value '10'. These may be communicated with or without hyphens, and can be checked for their validity by the following formula:
+
+```text
+(x1 * 10 + x2 * 9 + x3 * 8 + x4 * 7 + x5 * 6 + x6 * 5 + x7 * 4 + x8 * 3 + x9 * 2 + x10 * 1) mod 11 == 0
+```
+
+If the result is 0, then it is a valid ISBN-10, otherwise it is invalid.
+
+## Example
+
+Let's take the ISBN-10 `3-598-21508-8`. We plug it in to the formula, and get:
+
+```text
+(3 * 10 + 5 * 9 + 9 * 8 + 8 * 7 + 2 * 6 + 1 * 5 + 5 * 4 + 0 * 3 + 8 * 2 + 8 * 1) mod 11 == 0
+```
+
+Since the result is 0, this proves that our ISBN is valid.
+
+## Task
+
+Given a string the program should check if the provided string is a valid ISBN-10.
+Putting this into place requires some thinking about preprocessing/parsing of the string prior to calculating the check digit for the ISBN.
+
+The program should be able to verify ISBN-10 both with and without separating dashes.
+
+## Caveats
+
+Converting from strings to numbers can be tricky in certain languages.
+Now, it's even trickier since the check digit of an ISBN-10 may be 'X' (representing '10'). For instance `3-598-21507-X` is a valid ISBN-10.
+
+## Bonus tasks
+
+* Generate a valid ISBN-13 from the input ISBN-10 (and maybe verify it again with a derived verifier).
+
+* Generate valid ISBN, maybe even from a given starting ISBN.
+
+## Source
+
+### Created by
+
+- @creaaa
+
+### Contributed to by
+
+- @bitfield
+- @ekingery
+- @ferhatelmas
+- @h311ion
+- @hilary
+- @kytrinyx
+- @leenipper
+- @sebito91
+- @tinsch
+
+### Based on
+
+Converting a string into a number and some basic processing utilizing a relatable real world example. - https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation

go/isbn-verifier/cases_test.go

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+package isbn
+
+// Source: exercism/problem-specifications
+// Commit: 3134243 isbn-verifier: Crafted input to catch more incorrect algorithms (#1255)
+// Problem Specifications Version: 2.7.0
+
+var testCases = []struct {
+	isbn        string
+	expected    bool
+	description string
+}{
+	{"3-598-21508-8", true, "valid isbn number"},
+	{"3-598-21508-9", false, "invalid isbn check digit"},
+	{"3-598-21507-X", true, "valid isbn number with a check digit of 10"},
+	{"3-598-21507-A", false, "check digit is a character other than X"},
+	{"3-598-P1581-X", false, "invalid character in isbn"},
+	{"3-598-2X507-9", false, "X is only valid as a check digit"},
+	{"3598215088", true, "valid isbn without separating dashes"},
+	{"359821507X", true, "isbn without separating dashes and X as check digit"},
+	{"359821507", false, "isbn without check digit and dashes"},
+	{"3598215078X", false, "too long isbn and no dashes"},
+	{"00", false, "too short isbn"},
+	{"3-598-21507", false, "isbn without check digit"},
+	{"3-598-21515-X", false, "check digit of X should not be used for 0"},
+	{"", false, "empty isbn"},
+	{"134456729", false, "input is 9 characters"},
+	{"3132P34035", false, "invalid characters are not ignored"},
+	{"98245726788", false, "input is too long but contains a valid isbn"},
+}

go/isbn-verifier/go.mod

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+module isbn
+
+go 1.13

go/isbn-verifier/isbn_verifier.go

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+package isbn
+
+func IsValidISBN(isbn string) bool {
+	panic("Please implement the IsValidISBN function")
+}

go/isbn-verifier/isbn_verifier_test.go

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+package isbn
+
+import (
+	"testing"
+)
+
+func TestIsValidISBN(t *testing.T) {
+	for _, test := range testCases {
+		observed := IsValidISBN(test.isbn)
+		if observed == test.expected {
+			t.Logf("PASS: %s", test.description)
+		} else {
+			t.Errorf("FAIL: %s\nIsValidISBN(%q)\nExpected: %t, Actual: %t",
+				test.description, test.isbn, test.expected, observed)
+		}
+	}
+}
+
+func BenchmarkIsValidISBN(b *testing.B) {
+	if testing.Short() {
+		b.Skip("skipping benchmark in short mode.")
+	}
+	for i := 0; i < b.N; i++ {
+		for _, n := range testCases {
+			IsValidISBN(n.isbn)
+		}
+	}
+}