feat(flags): add semver targeting to local evaluation by dmarticus · Pull Request #166 · PostHog/posthog-go

dmarticus · 2026-03-02T22:10:23Z

Summary

Add 9 semver comparison operators to the property matching logic used during local feature flag evaluation
Implement inline semver parsing without external dependencies (~170 lines)
Add comprehensive test coverage (~650 lines)

This matches the behavior already implemented in:

PostHog Python SDK: feat: add semver targeting support to local flag evaluation posthog-python#447
PostHog server: feat(flags): support semver comparisons in user_blast_radius posthog#44596

Operators Added

Operator	Description	Example
`semver_eq`	Exact match	1.2.3 == 1.2.3
`semver_neq`	Not equal	1.2.3 != 1.2.4
`semver_gt`	Greater than	1.2.4 > 1.2.3
`semver_gte`	Greater than or equal	1.2.3 >= 1.2.3
`semver_lt`	Less than	1.2.2 < 1.2.3
`semver_lte`	Less than or equal	1.2.3 <= 1.2.3
`semver_tilde`	Patch-level range	~1.2.3 → >=1.2.3 <1.3.0
`semver_caret`	Compatible-with range	^1.2.3 → >=1.2.3 <2.0.0
`semver_wildcard`	Wildcard range	1.2.* → >=1.2.0 <1.3.0

Semver Parsing

The SemanticVersion helper class handles:

v/V prefix stripping (v1.2.3 → 1.2.3)
Whitespace trimming
Pre-release suffix stripping (1.2.3-alpha → 1.2.3)
Build metadata stripping (1.2.3+build.123 → 1.2.3)
Partial versions (1.2 → 1.2.0)
Extra components ignored (1.2.3.4 → 1.2.3)

No external semver library is used—parsing is implemented inline per SDK guidelines.

Test plan

132 unit tests for SemanticVersion parsing and comparison
80 integration tests for semver operators in LocalEvaluator
All existing LocalEvaluator tests pass (258 total)
Build succeeds on both netstandard2.1 and net8.0
Tests cover all operators with true/false cases
Tests cover edge cases: v-prefix, whitespace, pre-release suffixes, partial versions, leading zeros
Tests cover error handling: missing keys, null values, invalid semver

🤖 Generated with Claude Code

github-actions · 2026-03-02T22:13:32Z

posthog-go Compliance Report

Date: 2026-03-04 23:16:06 UTC
Duration: 105789ms

✅ All Tests Passed!

29/29 tests passed

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	609ms
Format Validation.Event Has Uuid	✅	607ms
Format Validation.Event Has Lib Properties	✅	607ms
Format Validation.Distinct Id Is String	✅	607ms
Format Validation.Token Is Present	✅	607ms
Format Validation.Custom Properties Preserved	✅	607ms
Format Validation.Event Has Timestamp	✅	607ms
Retry Behavior.Retries On 503	✅	5612ms
Retry Behavior.Does Not Retry On 400	✅	2610ms
Retry Behavior.Does Not Retry On 401	✅	2609ms
Retry Behavior.Respects Retry After Header	✅	5614ms
Retry Behavior.Implements Backoff	✅	15623ms
Retry Behavior.Retries On 500	✅	5613ms
Retry Behavior.Retries On 502	✅	5612ms
Retry Behavior.Retries On 504	✅	5613ms
Retry Behavior.Max Retries Respected	✅	15620ms
Deduplication.Generates Unique Uuids	✅	616ms
Deduplication.Preserves Uuid On Retry	✅	5608ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10615ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5614ms
Deduplication.No Duplicate Events In Batch	✅	611ms
Deduplication.Different Events Have Different Uuids	✅	610ms
Compression.Sends Gzip When Enabled	✅	606ms
Batch Format.Uses Proper Batch Structure	✅	607ms
Batch Format.Flush With No Events Sends Nothing	✅	605ms
Batch Format.Multiple Events Batched Together	✅	611ms
Error Handling.Does Not Retry On 403	✅	2609ms
Error Handling.Does Not Retry On 413	✅	2609ms
Error Handling.Retries On 408	✅	5613ms

Copilot

Pull request overview

Adds semantic-version (semver) targeting support to the local feature flag evaluator, aligning Go SDK behavior with existing implementations in other PostHog components.

Changes:

Bump SDK version to 1.11.0.
Add 9 semver operators to matchProperty, plus inline semver parsing and range bound computation.
Add extensive unit/integration test coverage for semver parsing and operator behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
`version.go`	Version bump to reflect new feature flag targeting capabilities.
`featureflags.go`	Implements semver operators in `matchProperty` and adds semver parsing/range helpers.
`feature_flags_matching_test.go`	Adds parsing/comparison tests and operator-level matching tests for semver behavior.

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Copilot · 2026-03-04T21:56:35Z

featureflags.go

+
+		overrideParsed, err := parseSemver(overrideStr)
+		if err != nil {
+			return false, &InconclusiveMatchError{fmt.Sprintf("person property value '%s' is not a valid semver", overrideStr)}


The error message says "person property value", but matchProperty is used for both person and group properties and doesn't check the property type here. Consider changing this to a neutral "property value" (and likewise in the other semver operator branches) to avoid misleading diagnostics.

Suggested change

return false, &InconclusiveMatchError{fmt.Sprintf("person property value '%s' is not a valid semver", overrideStr)}

return false, &InconclusiveMatchError{fmt.Sprintf("property value '%s' is not a valid semver", overrideStr)}

Copilot · 2026-03-04T21:56:36Z

featureflags.go

+			return false, &InconclusiveMatchError{fmt.Sprintf("person property value '%s' is not a valid semver", overrideStr)}
+		}


The error message says "person property value", but matchProperty is used for both person and group properties and doesn't check the property type here. Consider changing this to a neutral "property value" to avoid misleading diagnostics.

Copilot · 2026-03-04T21:56:36Z

featureflags.go

+			return false, &InconclusiveMatchError{fmt.Sprintf("person property value '%s' is not a valid semver", overrideStr)}
+		}


The error message says "person property value", but matchProperty is used for both person and group properties and doesn't check the property type here. Consider changing this to a neutral "property value" to avoid misleading diagnostics.

Copilot · 2026-03-04T21:56:36Z

featureflags.go

+			return false, &InconclusiveMatchError{fmt.Sprintf("person property value '%s' is not a valid semver", overrideStr)}
+		}


The error message says "person property value", but matchProperty is used for both person and group properties and doesn't check the property type here. Consider changing this to a neutral "property value" to avoid misleading diagnostics.

Copilot · 2026-03-04T21:56:36Z

featureflags.go

+	if idx := strings.Index(text, "-"); idx >= 0 {
+		text = text[:idx]
+	}
+	if idx := strings.Index(text, "+"); idx >= 0 {
+		text = text[:idx]


The semver suffix stripping treats the first '-' or '+' anywhere in the string as a pre-release/build delimiter. This means malformed inputs like "1-2.3" or "1.-2.3" can be truncated and parsed as valid versions (e.g. "1"). Consider validating the core version format (digits/dots only) before stripping suffixes so invalid cores fail parsing instead of silently changing meaning.

Copilot · 2026-03-04T21:56:37Z

featureflags.go

+	minor := 0
+	if len(parts) > 1 && parts[1] != "" {
+		minor, err = strconv.Atoi(parts[1])
+		if err != nil {
+			return semverTuple{}, fmt.Errorf("invalid semver: minor version '%s' is not a number", parts[1])


This logic defaults a missing/empty minor component to 0 (and similarly for patch below), which makes malformed strings like "1..3" or "1." parse successfully. If the intent is only to support shortened forms like "1" and "1.2", consider returning an error when a component is present but empty (i.e. a "." was provided with no digits).

- Change "person property value" to "property value" in error messages since matchProperty is used for both person and group properties - Validate core version format before stripping pre-release/build suffixes to reject malformed inputs like "1-2.3" or "-alpha" - Return error when a version component is present but empty (e.g., "1..3" or "1.") instead of silently defaulting to 0 - Add tests for newly rejected malformed inputs

add semver targeting to local evaluation

a0ae546

chore: bump version to 1.11.0 [version bump]

00dbb72

gustavohstrassburger requested a review from Copilot March 4, 2026 21:52

Copilot started reviewing on behalf of gustavohstrassburger March 4, 2026 21:52 View session

Copilot AI reviewed Mar 4, 2026

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gustavohstrassburger approved these changes Mar 4, 2026

View reviewed changes

dmarticus added 2 commits March 4, 2026 15:02

fix: run go fmt

0fe8af1

dmarticus merged commit 1e277f9 into master Mar 4, 2026
11 of 12 checks passed

dmarticus deleted the feat/semver-targeting branch March 4, 2026 23:23

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feat(flags): add semver targeting to local evaluation#166

feat(flags): add semver targeting to local evaluation#166
dmarticus merged 4 commits intomasterfrom
feat/semver-targeting

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	return false, &InconclusiveMatchError{fmt.Sprintf("person property value '%s' is not a valid semver", overrideStr)}
	return false, &InconclusiveMatchError{fmt.Sprintf("property value '%s' is not a valid semver", overrideStr)}

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dmarticus commented Mar 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Operators Added

Semver Parsing

Test plan

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dmarticus commented Mar 2, 2026 •

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