RequirementsTxtParser: attach ParseExceptionResult on resolution failure (#7326)

Author: Jenson3210

rewrite-python/src/main/java/org/openrewrite/python/RequirementsTxtParser.java

@@ -17,6 +17,7 @@
 
 import org.jspecify.annotations.Nullable;
 import org.openrewrite.ExecutionContext;
+import org.openrewrite.ParseExceptionResult;
 import org.openrewrite.Parser;
 import org.openrewrite.SourceFile;
 import org.openrewrite.python.internal.PyProjectHelper;
@@ -37,7 +38,6 @@
 import java.util.stream.Stream;
 
 import static java.util.Collections.emptyMap;
-
 import static org.openrewrite.Tree.randomId;
 
 /**
@@ -67,7 +67,7 @@ public RequirementsTxtParser(Map<String, String> subprocessEnvironment) {
     public Stream<SourceFile> parseInputs(Iterable<Input> sources, @Nullable Path relativeTo, ExecutionContext ctx) {
         return plainTextParser.parseInputs(sources, relativeTo, ctx).map(sf -> {
             if (!(sf instanceof PlainText)) {
-                return sf;
+                return sf.withMarkers(sf.getMarkers().add(ParseExceptionResult.build(this, new UnsupportedOperationException(), "Creating a PythonResolutionResult can only be done for PlainText LST elements.")));
             }
             PlainText text = (PlainText) sf;
 
@@ -78,12 +78,15 @@ public Stream<SourceFile> parseInputs(Iterable<Input> sources, @Nullable Path re
             Path workspace = DependencyWorkspace.getOrCreateRequirementsWorkspace(
                     text.getText(), originalFilePath, subprocessEnvironment);
             if (workspace == null) {
-                return sf;
+                return sf.withMarkers(sf.getMarkers().add(ParseExceptionResult.build(this, new UnsupportedOperationException(),
+                        "Failed to create the PythonResolutionResult due to a failure to install the requirement file. " +
+                                "Perhaps you are missing `uv` in the environment or trying to build a requirement text file containing dependencies which are not available?")));
             }
 
             List<ResolvedDependency> resolvedDeps = parseFreezeOutput(workspace);
             if (resolvedDeps.isEmpty()) {
-                return sf;
+                return sf.withMarkers(sf.getMarkers().add(ParseExceptionResult.build(this, new UnsupportedOperationException(),
+                        "Failed to create the PythonResolutionResult: no resolved dependencies.")));
             }
 
             List<Dependency> deps = dependenciesFromResolved(resolvedDeps,

rewrite-python/src/test/java/org/openrewrite/python/RequirementsTxtParserTest.java

@@ -18,6 +18,7 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 import org.openrewrite.InMemoryExecutionContext;
+import org.openrewrite.ParseExceptionResult;
 import org.openrewrite.Parser;
 import org.openrewrite.SourceFile;
 import org.openrewrite.python.internal.UvExecutor;
@@ -263,6 +264,29 @@ void markerContainsDependenciesFromFreeze() {
         assertThat(marker.getPackageManager()).isEqualTo(PythonResolutionResult.PackageManager.Uv);
     }
 
+    @Test
+    void unresolvableRequirementsAttachesParseExceptionMarker() {
+        // A non-existent package will fail to install regardless of whether uv is present
+        // (without uv, workspace creation fails; with uv, the install itself fails).
+        String requirements = "this-package-definitely-does-not-exist-zzz==9.9.9\n";
+
+        RequirementsTxtParser parser = new RequirementsTxtParser();
+        Parser.Input input = Parser.Input.fromString(Paths.get("requirements.txt"), requirements);
+        List<SourceFile> parsed = parser.parseInputs(
+                Collections.singletonList(input),
+                null,
+                new InMemoryExecutionContext(t -> {})
+        ).collect(Collectors.toList());
+
+        assertThat(parsed).hasSize(1);
+        SourceFile sf = parsed.get(0);
+        ParseExceptionResult marker = sf.getMarkers().findFirst(ParseExceptionResult.class).orElse(null);
+        assertThat(marker).isNotNull();
+        assertThat(marker.getMessage()).contains("PythonResolutionResult");
+        // Should not have a successful resolution marker
+        assertThat(sf.getMarkers().findFirst(PythonResolutionResult.class)).isEmpty();
+    }
+
     @Test
     void builderCreatesDslName() {
         RequirementsTxtParser.Builder builder = RequirementsTxtParser.builder();