NO-JIRA: tests(buildinputs) implement a heredoc.Doc() helper to dedent backtick-strings (opendatahub-io#2522)

Author: jiridanek

scripts/buildinputs/buildinputs_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"os"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strings"
 	"testing"

scripts/buildinputs/go.mod

@@ -4,6 +4,7 @@ go 1.24
 
 require (
 	github.com/containerd/platforms v1.0.0-rc.1
+	github.com/google/go-cmp v0.7.0
 	github.com/moby/buildkit v0.23.2
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.1.1

scripts/buildinputs/heredoc.go

@@ -0,0 +1,62 @@
+// llm-powered reimplementation of github.com/MakeNowJust/heredoc
+package main
+
+import (
+	"math"
+	"strings"
+)
+
+// Doc removes common leading whitespace from every line in a string.
+func Doc(s string) string {
+	lines := strings.Split(s, "\n")
+	minIndent := math.MaxInt32
+
+	// First, find the minimum indentation of non-empty lines.
+	for _, line := range lines {
+		if len(strings.TrimSpace(line)) == 0 {
+			continue // Skip empty or whitespace-only lines
+		}
+
+		indent := 0
+		for _, r := range line {
+			if r == ' ' || r == '\t' {
+				indent++
+			} else {
+				break
+			}
+		}
+
+		if indent < minIndent {
+			minIndent = indent
+		}
+	}
+
+	// If no common indentation is found, return the original string.
+	if minIndent == math.MaxInt32 {
+		return s
+	}
+
+	// Create a builder to efficiently construct the new string.
+	var builder strings.Builder
+	for i, line := range lines {
+		if i == 0 && line == "" {
+			continue // Skip the first line if it's empty.
+		}
+		if len(strings.TrimSpace(line)) == 0 {
+			if i != len(lines)-1 {
+				// Unless this is the last line, in which case we drop trailing whitespace.
+				builder.WriteString(line) // Keep empty lines as they are.
+			}
+		} else {
+			// Trim the minimum common indentation from the start of the line.
+			builder.WriteString(line[minIndent:])
+		}
+
+		// Add the newline back, except for the very last line.
+		if i < len(lines)-1 {
+			builder.WriteString("\n")
+		}
+	}
+
+	return builder.String()
+}

scripts/buildinputs/heredoc_test.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestDoc(t *testing.T) {
+	input := `
+		a
+		b
+	`
+	diff(t, "a\nb\n", Doc(input))
+}
+
+// diff errors with a diff between expected and actual if they are not equal.
+func diff(t *testing.T, expected, actual string) {
+	t.Helper()
+	if diff := cmp.Diff(expected, actual); diff != "" {
+		t.Errorf("mismatch (-want +got):\n%s", diff)
+	}
+}