From cbe2e205dac99f20afff4ccdeca21fd10d596565 Mon Sep 17 00:00:00 2001
From: Bradley Burns <56638814+bradb423@users.noreply.github.com>
Date: Sat, 22 Jan 2022 20:14:23 +0000
Subject: feat: add "lcov" command for generating LCOV reports

* Add LCOV functionality into coverage.py

* Add testing for the LCOV reporter

* Add documentation for the LCOV reporter
---
 coverage/lcovreport.py | 106 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 coverage/lcovreport.py

(limited to 'coverage/lcovreport.py')

diff --git a/coverage/lcovreport.py b/coverage/lcovreport.py
new file mode 100644
index 00000000..5a49ac4a
--- /dev/null
+++ b/coverage/lcovreport.py
@@ -0,0 +1,106 @@
+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
+
+"""LCOV reporting for coverage.py."""
+
+import sys
+import base64
+from hashlib import md5
+
+from coverage.report import get_analysis_to_report
+
+
+class LcovReporter:
+    """A reporter for writing LCOV coverage reports."""
+
+    report_type = "LCOV report"
+
+    def __init__(self, coverage):
+        self.coverage = coverage
+        self.config = self.coverage.config
+
+    def report(self, morfs, outfile=None):
+        """Renders the full lcov report
+
+        'morfs' is a list of modules or filenames
+
+        outfile is the file object to write the file into.
+        """
+
+        self.coverage.get_data()
+        outfile = outfile or sys.stdout
+
+        for fr, analysis in get_analysis_to_report(self.coverage, morfs):
+            self.get_lcov(fr, analysis, outfile)
+
+    def get_lcov(self, fr, analysis, outfile=None):
+        """Produces the lcov data for a single file
+
+        get_lcov currently supports both line and branch coverage,
+        however function coverage is not supported.
+
+        """
+
+        outfile.write("TN:\n")
+        outfile.write(f"SF:{fr.relative_filename()}\n")
+        source_lines = fr.source().splitlines()
+        for covered in sorted(analysis.executed):
+            # Note: Coveragepy currently only supports checking *if* a line has
+            # been executed, not how many times, so we set this to 1 for nice
+            # output even if it's technically incorrect
+
+            # The lines below calculate a 64 bit encoded md5 hash of the line
+            # corresponding to the DA lines in the lcov file,
+            # for either case of the line being covered or missed in Coveragepy
+            # The final two characters of the encoding ("==") are removed from
+            # the hash to allow genhtml to run on the resulting lcov file
+            if source_lines:
+                line = source_lines[covered - 1].encode("utf-8")
+            else:
+                line = b""
+            hashed = str(base64.b64encode(md5(line).digest())[:-2], encoding="utf-8")
+            outfile.write(f"DA:{covered},1,{hashed}\n")
+        for missed in sorted(analysis.missing):
+            if source_lines:
+                line = source_lines[missed - 1].encode("utf-8")
+            else:
+                line = b""
+            hashed = str(base64.b64encode(md5(line).digest())[:-2], encoding="utf-8")
+            outfile.write(f"DA:{missed},0,{hashed}\n")
+        outfile.write(f"LF:{len(analysis.statements)}\n")
+        outfile.write(f"LH:{len(analysis.executed)}\n")
+
+        # More information dense branch coverage data
+        missing_arcs = analysis.missing_branch_arcs()
+        executed_arcs = analysis.executed_branch_arcs()
+        for block_number, block_line_number in enumerate(
+            sorted(analysis.branch_stats().keys())
+        ):
+            for branch_number, line_number in enumerate(
+                sorted(missing_arcs[block_line_number])
+            ):
+                # The exit branches have a negative line number,
+                # this will not produce valid lcov, and so setting
+                # the line number of the exit branch to 0 will allow
+                # for valid lcov, while preserving the data
+                line_number = max(line_number, 0)
+                outfile.write(f"BRDA:{line_number},{block_number},{branch_number},-\n")
+            # The start value below allows for the block number to be
+            # preserved between these two for loops (stopping the loop from
+            # resetting the value of the block number to 0)
+            for branch_number, line_number in enumerate(
+                sorted(executed_arcs[block_line_number]),
+                start=len(missing_arcs[block_line_number]),
+            ):
+                line_number = max(line_number, 0)
+                outfile.write(f"BRDA:{line_number},{block_number},{branch_number},1\n")
+
+        # Summary of the branch coverage
+        if analysis.has_arcs():
+            branch_stats = analysis.branch_stats()
+            brf = sum(t for t, k in branch_stats.values())
+            brh = brf - sum(t - k for t, k in branch_stats.values())
+            outfile.write(f"BRF:{brf}\n")
+            outfile.write(f"BRH:{brh}\n")
+
+        outfile.write("end_of_record\n")
-- 
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