feat(python): add Python/pytest support

go.mod

@@ -5,6 +5,7 @@ go 1.26.3
 require (
 	github.com/bmatcuk/doublestar/v4 v4.10.0
 	github.com/klauspost/cpuid/v2 v2.3.0
+	github.com/pelletier/go-toml/v2 v2.3.1
 	github.com/spf13/cobra v1.10.2
 	github.com/spf13/viper v1.21.0
 	github.com/stretchr/testify v1.11.1
@@ -19,7 +20,6 @@ require (
 	github.com/go-viper/mapstructure/v2 v2.5.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/pelletier/go-toml/v2 v2.3.1 // indirect
 	github.com/philhofer/fwd v1.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rogpeppe/go-internal v1.14.1 // indirect

internal/constants/app.go

@@ -13,6 +13,7 @@ const ManifestVersion = "1"
 var ManifestPath = filepath.Join(PlanDirectory, "manifest.txt")
 
 const TestOptimizationManifestFileEnvVar = "TEST_OPTIMIZATION_MANIFEST_FILE"
+const DDTestOptimizationManifestFileEnvVar = "DD_TEST_OPTIMIZATION_MANIFEST_FILE"
 
 // Runner layout paths.
 var RunnerDirectory = filepath.Join(PlanDirectory, "runner")
@@ -36,3 +37,4 @@ var HTTPCacheDir = filepath.Join(PlanDirectory, "cache", "http")
 
 // Platform specific output file paths
 var RubyEnvOutputPath = filepath.Join(PlanDirectory, "ruby_env.json")
+var PythonEnvOutputPath = filepath.Join(PlanDirectory, "python_env.json")

internal/framework/pytest.go

@@ -0,0 +1,116 @@
+package framework
+
+import (
+	"context"
+	"log/slog"
+	"maps"
+	"strings"
+
+	"github.com/DataDog/ddtest/internal/discovery"
+	"github.com/DataDog/ddtest/internal/ext"
+	"github.com/DataDog/ddtest/internal/settings"
+	"github.com/DataDog/ddtest/internal/testoptimization"
+)
+
+const (
+	// pytestDefaultPattern is used when no config file specifies testpaths/python_files.
+	// Matches both pytest conventions (test_*.py and *_test.py) everywhere in the tree.
+	pytestDefaultPattern = "**/{test_*,*_test}.py"
+)
+
+type PyTest struct {
+	executor        ext.CommandExecutor
+	commandOverride []string
+	platformEnv     map[string]string
+}
+
+func NewPytest() *PyTest {
+	return &PyTest{
+		executor:        &ext.DefaultCommandExecutor{},
+		commandOverride: loadCommandOverride(),
+		platformEnv:     make(map[string]string),
+	}
+}
+
+func (p *PyTest) SetPlatformEnv(platformEnv map[string]string) {
+	p.platformEnv = platformEnv
+}
+
+func (p *PyTest) GetPlatformEnv() map[string]string {
+	return p.platformEnv
+}
+
+func (p *PyTest) Name() string {
+	return "pytest"
+}
+
+// TestPattern returns the glob pattern used to discover pytest test files.
+// Priority: explicit --tests-location flag > pytest config file > built-in default.
+// Multiple testpaths or python_files from config are collapsed into brace-expansion
+// syntax that doublestar handles natively, e.g. {tests,src}/**/{test_*,*_test}.py.
+func (p *PyTest) TestPattern() string {
+	if custom := settings.GetTestsLocation(); custom != "" {
+		return custom
+	}
+
+	cfg := loadPytestConfig()
+
+	filePatterns := cfg.PythonFiles
+	if len(filePatterns) == 0 {
+		filePatterns = []string{"{test_*,*_test}.py"}
+	}
+	filePart := braceExpand(filePatterns)
+
+	if len(cfg.Testpaths) == 0 {
+		return "**/" + filePart
+	}
+	return braceExpand(cfg.Testpaths) + "/**/" + filePart
+}
+
+func (p *PyTest) DiscoverTests(ctx context.Context, testFiles discovery.TestFileSet) ([]testoptimization.Test, error) {
+	discovery.Cleanup()
+
+	if testFiles.Empty() {
+		return []testoptimization.Test{}, nil
+	}
+
+	args := []string{"-m", "pytest"}
+
+	if testFiles.UseExplicitFiles() {
+		args = append(args, testFiles.ExplicitFiles...)
+	} else {
+		// pytest has no --pattern flag; resolve the glob pattern to explicit files
+		files, err := discovery.DiscoverTestFiles(testFiles.Pattern, "")
+		if err != nil {
+			return nil, err
+		}
+		if len(files) == 0 {
+			return []testoptimization.Test{}, nil
+		}
+		slog.Info("Constraining pytest test discovery", "pattern", testFiles.Pattern, "fileCount", len(files))
+		args = append(args, files...)
+	}
+
+	return discovery.DiscoverTests(ctx, p.executor, "python", args, p.platformEnv)
+}
+
+// braceExpand collapses a list into a single glob token.
+// A single item is returned as-is; multiple items are wrapped: {a,b,c}.
+func braceExpand(items []string) string {
+	if len(items) == 1 {
+		return items[0]
+	}
+	return "{" + strings.Join(items, ",") + "}"
+}
+
+func (p *PyTest) RunTests(ctx context.Context, testFiles []string, envMap map[string]string) error {
+	command := "python"
+	args := []string{"-m", "pytest"}
+	slog.Info("Running tests with command", "command", command, "args", args)
+	args = append(args, testFiles...)
+
+	mergedEnv := make(map[string]string)
+	maps.Copy(mergedEnv, p.platformEnv)
+	maps.Copy(mergedEnv, envMap)
+	return p.executor.Run(ctx, command, args, mergedEnv)
+}

internal/framework/pytest_config.go

@@ -0,0 +1,133 @@
+package framework
+
+import (
+	"bufio"
+	"bytes"
+	"os"
+	"strings"
+
+	"github.com/pelletier/go-toml/v2"
+)
+
+// pytestConfig holds the subset of pytest config relevant for test file discovery.
+type pytestConfig struct {
+	Testpaths   []string
+	PythonFiles []string
+}
+
+// loadPytestConfig reads testpaths and python_files from the first pytest config
+// file found, checking in pytest's own precedence order.
+// Returns a zero-value config when no file is found or no relevant keys are set.
+func loadPytestConfig() pytestConfig {
+	if data, err := os.ReadFile("pytest.ini"); err == nil {
+		if cfg, ok := parsePytestIni(data, "pytest"); ok {
+			return cfg
+		}
+	}
+	if data, err := os.ReadFile("pyproject.toml"); err == nil {
+		if cfg, ok := parsePyprojectToml(data); ok {
+			return cfg
+		}
+	}
+	if data, err := os.ReadFile("tox.ini"); err == nil {
+		if cfg, ok := parsePytestIni(data, "pytest"); ok {
+			return cfg
+		}
+	}
+	if data, err := os.ReadFile("setup.cfg"); err == nil {
+		if cfg, ok := parsePytestIni(data, "tool:pytest"); ok {
+			return cfg
+		}
+	}
+	return pytestConfig{}
+}
+
+// parsePytestIni extracts testpaths and python_files from an INI-format config.
+// section is the section name to look for (e.g. "pytest" or "tool:pytest").
+// Values may be space-separated on the same line, or newline-indented continuations.
+func parsePytestIni(data []byte, section string) (pytestConfig, bool) {
+	var cfg pytestConfig
+	inSection := false
+	var currentKey string
+	var currentValues []string
+
+	flush := func() {
+		switch currentKey {
+		case "testpaths":
+			cfg.Testpaths = currentValues
+		case "python_files":
+			cfg.PythonFiles = currentValues
+		}
+		currentKey = ""
+		currentValues = nil
+	}
+
+	scanner := bufio.NewScanner(bytes.NewReader(data))
+	for scanner.Scan() {
+		line := scanner.Text()
+		trimmed := strings.TrimSpace(line)
+
+		if trimmed == "" || strings.HasPrefix(trimmed, "#") || strings.HasPrefix(trimmed, ";") {
+			continue
+		}
+
+		if strings.HasPrefix(trimmed, "[") && strings.HasSuffix(trimmed, "]") {
+			flush()
+			inSection = trimmed[1:len(trimmed)-1] == section
+			continue
+		}
+
+		if !inSection {
+			continue
+		}
+
+		// Continuation lines are indented
+		if line[0] == ' ' || line[0] == '\t' {
+			currentValues = append(currentValues, strings.Fields(trimmed)...)
+			continue
+		}
+
+		idx := strings.IndexByte(trimmed, '=')
+		if idx < 0 {
+			continue
+		}
+		flush()
+		key := strings.TrimSpace(trimmed[:idx])
+		value := strings.TrimSpace(trimmed[idx+1:])
+		if key == "testpaths" || key == "python_files" {
+			currentKey = key
+			if value != "" {
+				currentValues = strings.Fields(value)
+			}
+		}
+	}
+	flush()
+
+	return cfg, len(cfg.Testpaths) > 0 || len(cfg.PythonFiles) > 0
+}
+
+type pyprojectTomlFile struct {
+	Tool struct {
+		Pytest struct {
+			IniOptions struct {
+				Testpaths   []string `toml:"testpaths"`
+				PythonFiles []string `toml:"python_files"`
+			} `toml:"ini_options"`
+		} `toml:"pytest"`
+	} `toml:"tool"`
+}
+
+func parsePyprojectToml(data []byte) (pytestConfig, bool) {
+	var parsed pyprojectTomlFile
+	if err := toml.Unmarshal(data, &parsed); err != nil {
+		return pytestConfig{}, false
+	}
+	opts := parsed.Tool.Pytest.IniOptions
+	if len(opts.Testpaths) == 0 && len(opts.PythonFiles) == 0 {
+		return pytestConfig{}, false
+	}
+	return pytestConfig{
+		Testpaths:   opts.Testpaths,
+		PythonFiles: opts.PythonFiles,
+	}, true
+}