libs/python: Remove DetectInterpreters (#2234)

## Changes
- Remove DetectInterpreters from DetectExecutable call: python3 or
python should always be on on the PATH. We don't need to detect
non-standard situations like python3.10 is present but python3 is not.
- I moved DetectInterpreters to cmd/labs where it is still used.

This is a follow up to https://github.com/databricks/cli/pull/2034

## Tests
Existing tests.

cmd/labs/project/installer.go

@@ -15,7 +15,6 @@ import (
 	"github.com/databricks/cli/libs/databrickscfg/profile"
 	"github.com/databricks/cli/libs/log"
 	"github.com/databricks/cli/libs/process"
-	"github.com/databricks/cli/libs/python"
 	"github.com/databricks/databricks-sdk-go"
 	"github.com/databricks/databricks-sdk-go/service/compute"
 	"github.com/databricks/databricks-sdk-go/service/sql"
@@ -223,7 +222,7 @@ func (i *installer) setupPythonVirtualEnvironment(ctx context.Context, w *databr
 	feedback := cmdio.Spinner(ctx)
 	defer close(feedback)
 	feedback <- "Detecting all installed Python interpreters on the system"
-	pythonInterpreters, err := python.DetectInterpreters(ctx)
+	pythonInterpreters, err := DetectInterpreters(ctx)
 	if err != nil {
 		return fmt.Errorf("detect: %w", err)
 	}

cmd/labs/project/interpreters.go

@@ -1,4 +1,4 @@
-package python
+package project
 
 import (
 	"context"

cmd/labs/project/interpreters_unix_test.go

@@ -1,6 +1,6 @@
 //go:build unix
 
-package python
+package project
 
 import (
 	"context"

cmd/labs/project/interpreters_win_test.go

@@ -1,6 +1,6 @@
 //go:build windows
 
-package python
+package project
 
 import (
 	"context"

libs/python/detect.go

@@ -39,27 +39,7 @@ func DetectExecutable(ctx context.Context) (string, error) {
 	//
 	// See https://github.com/pyenv/pyenv#understanding-python-version-selection
 
-	out, err := exec.LookPath(GetExecutable())
-
-	// most of the OS'es have python3 in $PATH, but for those which don't,
-	// we perform the latest version lookup
-	if err != nil && !errors.Is(err, exec.ErrNotFound) {
-		return "", err
-	}
-	if out != "" {
-		return out, nil
-	}
-	// otherwise, detect all interpreters and pick the least that satisfies
-	// minimal version requirements
-	all, err := DetectInterpreters(ctx)
-	if err != nil {
-		return "", err
-	}
-	interpreter, err := all.AtLeast("3.8")
-	if err != nil {
-		return "", err
-	}
-	return interpreter.Path, nil
+	return exec.LookPath(GetExecutable())
 }
 
 // DetectVEnvExecutable returns the path to the python3 executable inside venvPath,

libs/python/detect_unix_test.go

@@ -16,24 +16,16 @@ func TestDetectsViaPathLookup(t *testing.T) {
 	assert.NotEmpty(t, py)
 }
 
-func TestDetectsViaListing(t *testing.T) {
-	t.Setenv("PATH", "testdata/other-binaries-filtered")
-	ctx := context.Background()
-	py, err := DetectExecutable(ctx)
-	assert.NoError(t, err)
-	assert.Equal(t, "testdata/other-binaries-filtered/python3.10", py)
-}
-
 func TestDetectFailsNoInterpreters(t *testing.T) {
 	t.Setenv("PATH", "testdata")
 	ctx := context.Background()
 	_, err := DetectExecutable(ctx)
-	assert.Equal(t, ErrNoPythonInterpreters, err)
+	assert.Error(t, err)
 }
 
 func TestDetectFailsNoMinimalVersion(t *testing.T) {
 	t.Setenv("PATH", "testdata/no-python3")
 	ctx := context.Background()
 	_, err := DetectExecutable(ctx)
-	assert.EqualError(t, err, "cannot find Python greater or equal to v3.8.0")
+	assert.Error(t, err)
 }

libs/python/detect_win_test.go

@@ -20,5 +20,5 @@ func TestDetectFailsNoInterpreters(t *testing.T) {
 	t.Setenv("PATH", "testdata")
 	ctx := context.Background()
 	_, err := DetectExecutable(ctx)
-	assert.ErrorIs(t, err, ErrNoPythonInterpreters)
+	assert.Error(t, err)
 }