test(document links): add __has_embed integration tests

Cover both existing-file (produces link) and missing-file (no link)
cases for __has_embed directives.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/data/document_links/main.cpp

@@ -7,6 +7,14 @@ const char data[] = {
 #embed "data.bin"
 };
 
+#if __has_embed("data.bin")
+int has_embed_found = 1;
+#endif
+
+#if __has_embed("no_such_file.bin")
+int has_embed_not_found = 1;
+#endif
+
 int main() {
     return a + b + c;
 }

tests/integration/features/test_document_links.py

@@ -1,22 +1,30 @@
-"""Integration tests for document links with PCH and #embed.
+"""Integration tests for document links with PCH, #embed, and __has_embed.
 
 Verifies that document links from both PCH (preamble) and main-file
-compilation are correctly returned and merged, including #embed directives.
+compilation are correctly returned and merged, including #embed and
+__has_embed directives.
 
 Test source layout (tests/data/document_links/main.cpp):
 
-    #include "header_a.h"   <- line 0, in PCH preamble
-    #include "header_b.h"   <- line 1, in PCH preamble
-    int x = 1;              <- line 2, breaks preamble
-    #include "header_c.h"   <- line 3, NOT in PCH (after preamble break)
-                            <- line 4, empty
-    const char data[] = {   <- line 5
-    #embed "data.bin"       <- line 6, embed directive
-    };                      <- line 7
+    #include "header_a.h"              <- line 0, in PCH preamble
+    #include "header_b.h"              <- line 1, in PCH preamble
+    int x = 1;                         <- line 2, breaks preamble
+    #include "header_c.h"              <- line 3
+                                       <- line 4, empty
+    const char data[] = {              <- line 5
+    #embed "data.bin"                  <- line 6, embed directive
+    };                                 <- line 7
+                                       <- line 8, empty
+    #if __has_embed("data.bin")        <- line 9, has_embed (file exists)
+    int has_embed_found = 1;           <- line 10
+    #endif                             <- line 11
+                                       <- line 12, empty
+    #if __has_embed("no_such_file.bin") <- line 13, has_embed (file missing)
+    int has_embed_not_found = 1;       <- line 14
+    #endif                             <- line 15
 
-    int main() { ... }
-
-Expected: document_links returns 4 links total — 2 from PCH + 2 from main.
+Expected: 5 links from includes + embed + has_embed(existing),
+          __has_embed("no_such_file.bin") produces NO link.
 """
 
 from pathlib import Path
@@ -33,9 +41,13 @@ async def test_document_links_with_pch(client, workspace):
     assert links is not None, "document_links returned None"
 
     targets = sorted(Path(link.target).name for link in links)
-    assert targets == ["data.bin", "header_a.h", "header_b.h", "header_c.h"], (
-        f"Unexpected targets: {targets}"
-    )
+    assert targets == [
+        "data.bin",
+        "data.bin",
+        "header_a.h",
+        "header_b.h",
+        "header_c.h",
+    ], f"Unexpected targets: {targets}"
 
     client.close(uri)
 
@@ -59,17 +71,17 @@ async def test_document_links_pch_portion(client, workspace):
 
 @pytest.mark.workspace("document_links")
 async def test_document_links_main_portion(client, workspace):
-    """Main-file portion (header_c, data.bin) must appear in document links."""
+    """Main-file portion (header_c, data.bin x2) must appear in document links."""
     uri, _ = await client.open_and_wait(workspace / "main.cpp")
     links = await client.document_links(uri)
 
     main_links = [link for link in links if link.range.start.line >= 2]
-    assert len(main_links) == 2, (
-        f"Expected 2 main-file links (lines 3, 6), got {len(main_links)}"
+    assert len(main_links) == 3, (
+        f"Expected 3 main-file links (lines 3, 6, 9), got {len(main_links)}"
     )
 
     main_targets = sorted(Path(link.target).name for link in main_links)
-    assert main_targets == ["data.bin", "header_c.h"]
+    assert main_targets == ["data.bin", "data.bin", "header_c.h"]
 
     client.close(uri)
 
@@ -80,8 +92,47 @@ async def test_document_links_embed(client, workspace):
     uri, _ = await client.open_and_wait(workspace / "main.cpp")
     links = await client.document_links(uri)
 
-    embed_links = [link for link in links if Path(link.target).name == "data.bin"]
-    assert len(embed_links) == 1, f"Expected 1 embed link, got {len(embed_links)}"
-    assert embed_links[0].range.start.line == 6
+    embed_links = [
+        link
+        for link in links
+        if Path(link.target).name == "data.bin" and link.range.start.line == 6
+    ]
+    assert len(embed_links) == 1, (
+        f"Expected 1 embed link at line 6, got {len(embed_links)}"
+    )
+
+    client.close(uri)
+
+
+@pytest.mark.workspace("document_links")
+async def test_document_links_has_embed_exists(client, workspace):
+    """__has_embed with an existing file produces a document link."""
+    uri, _ = await client.open_and_wait(workspace / "main.cpp")
+    links = await client.document_links(uri)
+
+    has_embed_links = [
+        link
+        for link in links
+        if Path(link.target).name == "data.bin" and link.range.start.line == 9
+    ]
+    assert len(has_embed_links) == 1, (
+        f"Expected 1 has_embed link at line 9, got {len(has_embed_links)}"
+    )
+
+    client.close(uri)
+
+
+@pytest.mark.workspace("document_links")
+async def test_document_links_has_embed_missing(client, workspace):
+    """__has_embed with a non-existent file produces NO document link."""
+    uri, _ = await client.open_and_wait(workspace / "main.cpp")
+    links = await client.document_links(uri)
+
+    missing_links = [
+        link for link in links if Path(link.target).name == "no_such_file.bin"
+    ]
+    assert len(missing_links) == 0, (
+        f"Expected 0 links for non-existent file, got {len(missing_links)}"
+    )
 
     client.close(uri)