cloud.google.com/go v0.123.0: civil.Date, civil.DateTime, civil.ParseDate

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/cloud.google.com/go@v0.123.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/cloud.google.com/go@v0.123.0

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:069d20bc39ae4ed00c9f9e534f6e7f2746e59a4340a43928a3cc7d5ccb53598f","contract":["civil.ParseDate parses RFC3339 date strings into Date","civil.Date.AddDays correctly adds positive and negative days across month boundaries","civil.Date.DaysSince computes the number of days between two dates","civil.Date.IsValid detects invalid dates such as leap day in non-leap years","civil.ParseTime parses valid time strings and rejects invalid values","civil.DateTime combines Date and Time and supports Before and After comparison"],"goal":"verify pkg:golang/cloud.google.com/go@v0.123.0","kind":"HOW","packages":["pkg:golang/cloud.google.com/go@v0.123.0"],"schemaVersion":1,"symbols":["cloud.google.com/go/civil.Date","cloud.google.com/go/civil.DateTime","cloud.google.com/go/civil.ParseDate","cloud.google.com/go/civil.ParseTime","cloud.google.com/go/civil.Time"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/cloud.google.com/go@v0.123.0"],"schemaVersion":1,"subject":"pkg:golang/cloud.google.com/go@v0.123.0","symbols":["cloud.google.com/go/civil.Date","cloud.google.com/go/civil.DateTime","cloud.google.com/go/civil.ParseDate","cloud.google.com/go/civil.ParseTime","cloud.google.com/go/civil.Time"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require cloud.google.com/go v0.123.0

cloud.google.com/go v0.123.0 h1:2NAUJwPR47q+E35uaJeYoNhuNEM9kM8SjgRgdeOJUSE=
cloud.google.com/go v0.123.0/go.mod h1:xBoMV08QcqUGuPW65Qfm1o9Y4zKZBpGS+7bImXLTAZU=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=

package main

import (
	"fmt"
	"time"

	"cloud.google.com/go/civil"
)

func main() {
	// Parse a civil date
	d, err := civil.ParseDate("2026-10-10")
	if err != nil {
		panic(err)
	}
	fmt.Printf("Parsed Date: %s (Valid: %t)\n", d.String(), d.IsValid())

	// Add days across month boundary
	dNext := d.AddDays(25)
	fmt.Printf("25 days later: %s (Days since: %d)\n", dNext.String(), dNext.DaysSince(d))

	// Parse a civil time
	t, err := civil.ParseTime("14:30:00.123456789")
	if err != nil {
		panic(err)
	}
	fmt.Printf("Parsed Time: %s (Hour: %d, Minute: %d)\n", t.String(), t.Hour, t.Minute)

	// Combine into civil DateTime
	dt := civil.DateTime{Date: d, Time: t}
	fmt.Printf("Civil DateTime: %s (In UTC: %s)\n", dt.String(), dt.In(time.UTC).Format(time.RFC3339Nano))
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/cloud.google.com/go@v0.123.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/cloud.google.com/go@v0.123.0"
  ],
  "symbols": [
    "cloud.google.com/go/civil.Date",
    "cloud.google.com/go/civil.DateTime",
    "cloud.google.com/go/civil.ParseDate",
    "cloud.google.com/go/civil.ParseTime",
    "cloud.google.com/go/civil.Time"
  ],
  "runtimeConditions": {
    "ecosystem": "golang",
    "language": "go",
    "packageManager": "go@1.26.6",
    "runtime": "go@1.26.6"
  }
}

package main

import (
	"fmt"
	"os"
	"time"

	"cloud.google.com/go/civil"
)

func main() {
	// Assertion 1: civil.ParseDate parses RFC3339 date strings into Date
	d, err := civil.ParseDate("2026-10-10")
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: ParseDate returned error: %v\n", err)
		os.Exit(1)
	}
	expectedDate := civil.Date{Year: 2026, Month: time.October, Day: 10}
	if d != expectedDate {
		fmt.Fprintf(os.Stderr, "FAIL: ParseDate mismatch: got %+v, want %+v\n", d, expectedDate)
		os.Exit(1)
	}

	// Assertion 2: civil.Date.AddDays correctly adds positive and negative days across month boundaries
	dNext := d.AddDays(25)
	expectedNext := civil.Date{Year: 2026, Month: time.November, Day: 4}
	if dNext != expectedNext {
		fmt.Fprintf(os.Stderr, "FAIL: AddDays positive mismatch: got %+v, want %+v\n", dNext, expectedNext)
		os.Exit(1)
	}
	dPrev := dNext.AddDays(-25)
	if dPrev != d {
		fmt.Fprintf(os.Stderr, "FAIL: AddDays negative mismatch: got %+v, want %+v\n", dPrev, d)
		os.Exit(1)
	}

	// Assertion 3: civil.Date.DaysSince computes the number of days between two dates
	days := dNext.DaysSince(d)
	if days != 25 {
		fmt.Fprintf(os.Stderr, "FAIL: DaysSince mismatch: got %d, want 25\n", days)
		os.Exit(1)
	}

	// Assertion 4: civil.Date.IsValid detects invalid dates such as leap day in non-leap years
	validDate := civil.Date{Year: 2024, Month: time.February, Day: 29}
	if !validDate.IsValid() {
		fmt.Fprintf(os.Stderr, "FAIL: expected 2024-02-29 to be valid\n")
		os.Exit(1)
	}
	invalidDate := civil.Date{Year: 2023, Month: time.February, Day: 29}
	if invalidDate.IsValid() {
		fmt.Fprintf(os.Stderr, "FAIL: expected 2023-02-29 to be invalid\n")
		os.Exit(1)
	}

	// Assertion 5: civil.ParseTime parses valid time strings and rejects invalid values
	t, err := civil.ParseTime("14:30:00.123456789")
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: ParseTime returned error: %v\n", err)
		os.Exit(1)
	}
	expectedTime := civil.Time{Hour: 14, Minute: 30, Second: 0, Nanosecond: 123456789}
	if t != expectedTime {
		fmt.Fprintf(os.Stderr, "FAIL: ParseTime mismatch: got %+v, want %+v\n", t, expectedTime)
		os.Exit(1)
	}
	if _, err := civil.ParseTime("25:00:00"); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: ParseTime accepted invalid hour\n")
		os.Exit(1)
	}

	// Assertion 6: civil.DateTime combines Date and Time and supports Before and After comparison
	dt1 := civil.DateTime{Date: d, Time: t}
	dt2 := civil.DateTime{Date: dNext, Time: t}
	if !dt1.Before(dt2) {
		fmt.Fprintf(os.Stderr, "FAIL: expected dt1 to be before dt2\n")
		os.Exit(1)
	}
	if !dt2.After(dt1) {
		fmt.Fprintf(os.Stderr, "FAIL: expected dt2 to be after dt1\n")
		os.Exit(1)
	}

	fmt.Println("All civil contract assertions passed.")
}