From 5a7353945dd210ab97ff57e969652171b068726e Mon Sep 17 00:00:00 2001
From: Maxim Lebedev <git@toby3d.me>
Date: Tue, 9 Apr 2024 05:16:27 +0500
Subject: [PATCH] :technologist: Created function package with Must utility

---
 function/must.go      | 16 ++++++++++++++++
 function/must_test.go | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 function/must.go
 create mode 100644 function/must_test.go

diff --git a/function/must.go b/function/must.go
new file mode 100644
index 0000000..25b2d36
--- /dev/null
+++ b/function/must.go
@@ -0,0 +1,16 @@
+package function
+
+// Must initiates a panic if the function provided in it returns an error.
+//
+// See [regexp.MustCompile] as an example of how to use it.
+//
+// WARN(toby3d): this utility should only be used for data provided by the
+// developer side. Any data from other sources should be handled in the regular
+// way.
+func Must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+
+	return v
+}
diff --git a/function/must_test.go b/function/must_test.go
new file mode 100644
index 0000000..ceab015
--- /dev/null
+++ b/function/must_test.go
@@ -0,0 +1,33 @@
+package function_test
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"testing"
+
+	"source.toby3d.me/toby3d/hacks/function"
+)
+
+func TestMust(t *testing.T) {
+	t.Parallel()
+
+	testFunc := func(input string) (result [2]float64, err error) {
+		coords := strings.Split(input, ",")
+		if len(coords) < 2 {
+			return result, fmt.Errorf("got '%s', want input in format '9.999,9.999'", input)
+		}
+
+		for i := 0; i < 2; i++ {
+			if result[i], err = strconv.ParseFloat(coords[i], 64); err != nil {
+				return result, fmt.Errorf("cannot parse coordinate '%s': %w", coords[i], err)
+			}
+		}
+
+		return result, nil
+	}
+
+	if actual := function.Must(testFunc("1.23,9.87")); len(actual) != 2 {
+		t.Errorf("want 2 lenght float array, got %v", actual)
+	}
+}