Add black-box e2e suite pinning the CLI config contract

[korya]

Problem

Removing viper (#54) would be a leap of faith: nothing tests how http-assert resolves configuration, and main.go has zero coverage.

The 39% figure was not a testing-effort problem — it was one architectural fact showing up as a number. assertions.go and utils.go were already at 100%; every single function at 0.0% lived in main.go, unreachable because die() calls os.Exit and terminates the process on every error path. So the code that resolves flags, reads the environment, builds the request and renders failures was entirely unverified, and a refactor of it had nothing to check itself against.

Solution

Add a black-box suite that drives the compiled binary and pins all 19 config options across the command line and the environment.

Every test asserts only on exit code, stdout and stderr. Nothing references package internals, so the suite must keep passing verbatim across #54, #55 and #56 — that property is the deliverable, not a side effect.

Coverage:

	Before	After
Total	39.0%	99.3%
main.go functions at 0.0%	18 of 22	2 (logWarn, logError — dead, no callers)

The binary is built with -cover; its counters merge with the unit-test profile via go tool covdata, so subprocess execution counts. Coverage is now literally 100% minus the dead code.

The contract

TestE2EConfigContract runs all 19 options × {unset, command line, environment}. The unset and cli cases are a built-in mutation check — a vacuous predicate fails one of them, so the matrix cannot pass by being empty.

Options	CLI	Env
verbose silent log-level insecure max-time maphost	✓	✓
request header data + all 10 assert-*	✓	✗

envSupported records what the tool does today, not what it should do. When #54 makes this uniform, flipping those 13 booleans is the diff that proves the change worked.

Two behaviours that would otherwise have been lost silently

HTTP_ASSERT_MAPHOST splits on whitespace, not commas. This is undocumented and counter-intuitive, and a reimplementation reaching for strings.Split(v, ",") — the obvious choice — breaks every multi-mapping user with nothing to catch it:

export HTTP_ASSERT_MAPHOST="a:80=h1:8443 b:80=h2:8080"   # two mappings
export HTTP_ASSERT_MAPHOST="a:80=h1:8443,b:80=h2:8080"   # one malformed mapping, exit 71

The decoy in TestE2EConfigEnvSliceSeparator is listed first and points at a dead port, so a pass proves both entries parsed rather than just the leading one.

A flag always beats the environment, asserted in both directions — a build that ignored the environment entirely would pass a one-directional test.

Characterised defects

e2e_known_issues_test.go pins 14 filed bugs (#17 #18 #19 #20 #22 #23 #25 #26 #27 #28 #31 #32 #33 #34). They are deliberately not t.Skip-able: when an issue is fixed the test fails, and that failure is the signal to update the expectation in the same commit. Each carries a greppable // Characterizes #NN comment and a characterizes(t, NN, …) tag, so go test -run TestKnown selects the set.

Writing them caught an error in my own earlier report: #33 was wrong. -H 'BareHeader' does not drop the header — it sends Bareheader: with an empty value. The original finding came from a case-sensitive grep against a canonicalised name. The issue now carries a dated correction and the real curl comparison.

201 leaf assertions across 36 tests. The suite adds ~10.7s to go test (0.5s unit-only → 11.3s total, measured with -count=1); most of that is the deliberate sleeps the --max-time and precedence cases need, since --max-time is integer-seconds. CI runs it three times — test, test-race, test-cover — and the job completes in 1m10s.

No visual change — this is a headless CLI.

Other Changes

• Justfile — test-cover and test-coverage now merge unit and end-to-end profiles; without this the e2e runs would report as uncovered. Adds test-cover-func for a per-function breakdown.
• README.md — the environment-variable section claimed the HTTP_ASSERT_ prefix works generally. Corrected to tabulate the six supported variables, name the command-line-only options, and state the precedence and whitespace-separator rules. Every claim is now asserted by the matrix, so docs and binary cannot drift apart without a test failing.

Related:

• Closes Test coverage is 39% with no end-to-end CLI tests #48
• Delete viper: 35 of 38 packages to read six environment variables #54
• Extract run() int and push os.Exit to the edge #55
• Give assertions a structured result instead of an opaque error #56
• -H with no colon sends an empty-valued header instead of being rejected #33

🤖 Generated with Claude Code