NervesGithubUpdater.VersionCompare (nerves_github_updater v0.1.0)

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Compare a GitHub release tag against the device's current firmware version.

Pure functions; intended for use by view helpers that need to decide whether to show an "Update available" or "Up to date" badge. Lives outside the LiveView so it's unit-testable without standing up the full LiveView render pipeline.

Single source of truth

compare/2 is the only function that actually inspects the strings. update_available?/2 and up_to_date?/2 are thin boolean wrappers over it — there is no second parse-and-fallback path elsewhere.

Comparison rules

Both sides are normalized by stripping a single leading v (so "v1.2.3" ≡ "1.2.3") and then parsed with Version.parse/1.

  • Either side is nil (no release fetched yet, or no firmware version reported): :missing. Both boolean wrappers return false for this — we can't offer an update we don't have.
  • Both parse as semver: result of Version.compare/2.
  • Equal after normalization, but unparseable: :eq (so a tag like "nightly-abc" matching itself reads as "up to date").
  • Otherwise: :incomparable. Treated by update_available?/2 as "show the option" (matches pre-semver string-inequality behavior — better to offer an update we're unsure about than to hide it on an unparseable tag).

Summary

Types

result()

Functions

compare(release_tag, current_version)

Compare a release tag against a current firmware version. Returns one of

up_to_date?(release_tag, current_version)

true when the device is at or ahead of the latest release. The "ahead" case is collapsed into the same bucket as "equal" — there is no distinct "ahead of latest release" UI state.

update_available?(release_tag, current_version)

true when the release is strictly newer than the device. A downgrade (release older than device) returns false — that's the bug this module exists to prevent.

Types

result()

@type result() :: :gt | :eq | :lt | :missing | :incomparable

Functions

compare(release_tag, current_version)

@spec compare(String.t() | nil, String.t() | nil) :: result()

Compare a release tag against a current firmware version. Returns one of:

  • :gt — release is newer than the device
  • :eq — same
  • :lt — release is older than the device
  • :missing — either input is nil
  • :incomparable — both inputs are present but at least one doesn't parse as semver, and the normalized strings don't match

up_to_date?(release_tag, current_version)

@spec up_to_date?(String.t() | nil, String.t() | nil) :: boolean()

true when the device is at or ahead of the latest release. The "ahead" case is collapsed into the same bucket as "equal" — there is no distinct "ahead of latest release" UI state.

update_available?(release_tag, current_version)

@spec update_available?(String.t() | nil, String.t() | nil) :: boolean()

true when the release is strictly newer than the device. A downgrade (release older than device) returns false — that's the bug this module exists to prevent.

When versions can't be compared (e.g. nightly tags), we err on the side of showing the option rather than hiding it.